Most charity shops don't accept electrical goods (because they haven't got a qualified electrician to carry out the necessary safety test before they can be sold).
However the British Heart Foundation have over 50 large 'Furniture & Electrical' stores across the country. Even if you've not got such a store in your area, your local 'ordinary' BHF shop should still be able to accept the TVs, which will then be passed on to the nearest shop which sells electrical goods.
BHF usually have little difficulty in selling analogue TVs which have Scart sockets. Those without Scart sockets are harder for them to sell (because it's impossible to directly connect an ordinary Freeview box top them). However they can probably still get a few pounds for them.
Enter your postcode, here, to find your nearest BHF Furniture & Electrical shop (or, alternatively, their nearest 'ordinary' shop):
http://preview.multimap.com/clients/places.cgi ?client=heart
Chris