score:4
Depending on where you are going, you might first want to decide which UK network to use. In rural areas, coverage can be quite patchy and choosing a network with good coverage at your location will be relevant.
I got a 70GB EE pay as you go card last week for 20£. It was a matter of about 10 minutes in an EE shop to buy and activate the SIM. Other (virtual) operators will have similar deals. There is no requirement to be a UK resident.
Upvote:1
Smarty mobile seems like a good option. They offer no contract, data-only sims with no credit checks either.
Here are the prices:
To be on the safe side, I would go with the 15GB option as you may run out if you choose the 2GB one. I have no affiliation with Smarty mobile.