Air Salvage International at the Cotswolds Airport, Gloucestershire, first thing I can think of. I have seen the place from a distance and there are signs on the fence saying £1000 fine if caught in there. I'm guessing that it is criminal trespass being part of an active airport.
There's a farm near to Birlingham, Worcestershire, that has a collection of planes in it's yard.
Seen here in Google maps. Permission visits are possible. Do not just wander in, he will let you look if you ask! Gloster Meteor, Vampire and Hawker Hunter and others seen here.
This
website will be of interest but mostly international. The big famous boneyard in the States which has thousands of plane wrecks is called AMARG and has a
wikipedia page.
It looks as if I'm off to Albania soon myself for exploring, and I am aware of the entire Albanian Air Force which has been
grounded since 2005 at Kucove. Doubt that I will get a report up as parts of that airbase now used by an Italian Air Force detachment. It has featured on the Top Gear programme