Thanks for all the responses.
Ken - Will send a message later. Good tip about the post offices.

Numisrob - I didn't think UK banks would change money unless you had an account? Good to know about the self-serve at Sainsbury's etc. I was thinking of getting bulk coins from the arcades (will be at Blackpool for a day) but was worried I'd be stuck with half a ton of 10p coins I couldn't get rid of.

I noticed 1 arcade had a machine that took 5 or 10 quid notes and dispensed 10p coins. Will PM you once I'm in the UK.
AndyG - Which part of the midlands do you hail from? Will be staying at Tarrington, then Derbyshire, then Croston and Atwick.
Ta