Charities

Gifts to registered UK charities this can including religious bodies, Educational establishments, medical research Art Gallery's, Museums, cats homes or even Save the Narwhale.

If they are registered then that's it - it can also include charities not so registered the definition being 'any body of persons established for charitable purposes only' If in any doubt contact the charity you are considering and confirm their status they will be very pleased to hear from you and first at the door on your demise

UK National Bodies

These include
Most national Museums and Art Galleries, The National Trust etc again check if in doubt You can also make gifts to some Health services, Universities and colleges and Local Authorities.
Bizarrely you can also make gifts to any government department - perhaps the Inland Revenue might be good choice - or not

Gifts to UK Housing Associations

Exempt