When I made my will, I had gone to my daughter's office about something else[ she is a solicitor]
She asked if I had a will and when I replied in the negative, she said, come in sit down it wont take long! It didn't because it is straightforward.
When I asked how much, she said, nothing now, just leave at least £100 to Cancer Research when you die.
I do not know if this sort of arrangement can still happen. It's worth an ask!
Kooky