Nothing is better than Starbucks. Except DavidsTea, but you don't have that in the UK. But Starbucks is the best for writing, IMO. It's not like I want to eat while I'm writing, that's worse than eating watching TV. And even if I was really hungry, a piece of lemon bread will last for 4 hours of writing.
But you don't need a place to write. If you depend on having a place for writing you'll never write. You have to have the focus to just crack down and do it.