recycling old Apple laptops and legacy Apple Macintosh IT computer hardware in London or UK ?

Welcome Simon, and Happy New Year!

I think your best first step is to ask one of the Apple retail stores in London if they have a recommendation. A Mac User Group (MUG) may also be helpful. You can find a nearby group with this web page:

http://appleusergroupresources.com/find-a-group/

Some MUGs may have a list of people needing older computers who cannot otherwise afford them. Donation and reuse always beats recycling.

Allan

MUG = Mac Users Group, from this line in my first post:

A Mac User Group (MUG) may also be helpful.