During the Peninsula War, what British material aid was given to Spain/Portugal?

The most significant contribution that Britain made to the Portuguese and Spanish military was in the form of cash. This allowed them to recruit & pay their soldiers and supply them with food & equipment.

Between 1808 and 1814 Spain received a subsidy that averaged just over £1 million a year, considerably less than the Portuguese subsidy that was £1.5 million for the same period: in total Portugal received £10,605,689. (Even this amount represented only 57 per cent of the total cost of keeping the Portuguese army in the field; the rest was raised by the Portuguese government.)

^{Britain Against Napoleon}

Even prior to the French invasion of Portugal, the British had been supplying materiel to the Portuguese (who had been an British ally from the start of the French Revolutionary war).

Between 1796 and 1801 the shipments totalled some 32,500 muskets, 17,000 carbines (including 8,000 sergeants'), 6,300 pistols and 16,500 swords (including 3,500 for infantry and drummers), and 20 brass 12pdr field guns, with ammunition, accoutrements and equipments.

^{Armies of the Napoleonic Wars}

Following the occupation of Portugal by General Junot in 1807, when their army was disbanded, the Portuguese army had to be rebuilt.

To that end, in November 1808 Britain agreed to provide not only the money to pay 10,000 men, but also all arms, clothing and equipment for that number. This was doubled to 20,000 men in 1809, and increased yet again to 30,000 in January 1810 - in addition to providing the £130,000 necessary to increase the abysmal pay of Portuguese officers.

^{Armies of the Napoleonic Wars}

In addition, the Portuguese received help in other forms:

British support consisted not only of monetary subsidies, but also non-monetary donations, such as provisions, forage, firewood and equipment. The provisions included wheat, flour, bread, biscuits, rice, fresh meat, salted meat, salted fish, wine and spirits. The forage supplied was in the form of beans, barley, rye, peashoots, oats, corn, hay, seeds, straw and grass. The firewood was accompanied with oil and flints. The equipment sent was namely tents, tent poles, bottles, bottle straps, axes, lunch-boxes, hooks, as well as new and second-hand blankets.

^{The spending of states}

In contrast, at the start of the Peninsular War, the Spanish army numbered 100,000 men with an additional 30,000 men in the militia. The Spanish armies were organised by region and, on paper, looked quite formidable. The reality was that they were poorly paid, badly led and, consequently, of very low morale. The result was that they faired badly against the French and were a shadow of their former numbers by the time the Anglo-Portuguese army started to push into Spain in 1812.

In order to rebuild and re-equip the Spanish forces,

From 1812 Britain considerably augmented its already considerable aid to the Spanish Armies. As regard weapons, some 100,000 firearms (of which 95,000 were infantry muskets and 3,000 cavalry carbines) were send to Spain between April 1812 and March 1813 - up from about 40,000 stands of arms in 1811. In 1813 another 50,000 muskets were sent. To these were added thousands of cavalry sabres - 13,000 in 1812 alone - and thousands of pairs of cavalry pistols...Ordnance was also sent to Spain, though not in such massive numbers. It would seem that large calibre pieces were already available, but light-calibre 'mountain' cannons were in much demand by guerrilla bands, and the British tried to deliver these in numbers. When one adds uniforms and camp equipage for 100,000 infantry in 1812, for 50,000 men in 1813 and again in 1814, added to cavalry saddlery and supplies, the total logistical aid from Britain to Spain in the final years of the Napoleonic Wars was very impressive.

^{Armies of the Napoleonic Wars}

By their very nature the guerrilla forces were organised in a variety of ways and their arms were a mix of captured French weapons, home-made weapons and supplies from Britain. Consquently, the deliveries of supplies were more ad-hoc - some examples of these deliveries are:

Between September 1810 and September 1811, [Juan Diaz] Porlier's troops received '400 jackets, pantaloons, caps & c**kades' with '500 muskets and bayonets' and 200 sabres from the British.

In early 1811 the British managed to send 'for the use of Spanish Patriots of Guadalajara, vizt. 2,000 muskets, pouches and sets of accoutrements; medicines and surgical instruments &c for the 5,000 men, 2,000 blankets.'

In July 1811 James Johnson distributed some [supplies] to 'El Pastor, commanding the Volunteers of Guipozcoa (Guipuzcoa), to the number of 500, subject to the command of Mina...I gave them 100 muskets, 50 sabres, 10,000 ball cartridges, 5,000 pistol cartridges, 30 pistols, 1,000 flints, our pouches not being calculated for the sort of warfare carried on by the Guerrillas, he refused to take any.'

^{Armies of the Napoleonic Wars}

So in terms of weapons supplied to both the Spanish and Portuguese forces, the bulk was in the form of muskets (many of which came from EIC production in India). However, this represented only a small amount of the military aid that Britain supplied to these countries during the Peninsular War.

Edit: to answer a comment about the source of food aid, during the critical period from 1809 to 1812, the bulk of this came from North America.

Grain was an important commodity and was not readily available within Portugal or from Great Britain. Its main use was for the feeding of not only soldiers but it was a main staple for horses. American food supplies to the Peninsula, from 1808 to 1814, were critical...Throughout the summer of 1810 and 1811, unprecedented quantities of American wheat and flour, over one million barrels of flour alone, were shipped to the Peninsula.

^{The Duke of Wellington and the Supply System during the Peninsular War}

As the political situation between Britain and America worsened, to the point of war, alternative arrangements were investigated. This included shipping food supplies from the Barbary powers, Mexico, Brazil and allied Mediterranean states. However these were largely unsuccessful and the North American trade remained the predominant source up to 1813, when things changed.

In the summer of 1813 several factors combined to almost end this [grain] trade. Most important was the collapse of Napoleon's Continental System, which opened the Baltic ports and provided new sources of grain, which Britain immediately sought. Local purchases also increased once Wellington went on the offensive into Spain. Northern Spain was more fertile. Such abundance, which was not available to Wellington‘s army during the French occupation of Spain, ensured any trade embargo instituted from America would not cause Wellington's supplies to slow down...[due to careful planning] Despite being at war with a major supplier, America in 1812, no critical shortage was ever felt by Wellington's army.

^{The Duke of Wellington and the Supply System during the Peninsular War}

Sources:
Britain Against Napoleon, The Organisation of Victory 1793-1815, R.Knight (Penguin 2013)
Armies of the Napoleonic Wars, C.McNab (Osprey 2011)
The spending of states, Military expenditure during the long eighteenth century: patterns, organisation, and consequences, 1650-1815, Ed. S.Conway & R.T.Sánchez (VDM 2011)
The Duke of Wellington and the Supply System during the Peninsular War, Major T.T.Kirby, (Masters Thesis, Fort Leavenworth, 2011)