Upvote:1
You can return to Italy with your receipt, if the date of the receipt is less than 60 days from the date of expiration of your residence permit. Your flight must be directly to Italy without connecting in another Schengen territory.
Timatic, the database which airlines use to verify passenger travel documents, states in part:
- Residents of Italy with an expired Residence Permit are permitted to re-enter Italy. They must also have a receipt issued by the Italian Post Office or Police Department proving that they have applied for the new residence permit in less than 60 days after the expiration date. They must return to Italy directly from outside the Schengen area.
Of course you must have a Standard Visitor visa to enter the UK. Your residence permit gives you no right to enter there.