Having had a recent wake up call that I'm not immortal(!), I need to make a will. I'd like to leave a bequest to organisation(s) that support road racing, and/or road racers. The obvious one is the Rob Vine fund. The TT Marshalls association don't accept donations, and the Simon Andrews Fund is now closed. So are there any others that can accept donations? Thanks in advance.

A good idea! 
never thought of that myself,
maybe the Southern 100 supporters club? https://www.facebook.com/S100SupportersC...cale=en_GB
Friends of the TT riders association https://ttra.co.uk/fottra-index.htm
The Dan Kneen Charitable fund https://torq.im/
some that may fit the bill 
& Joey Dunlop Foundation, of course! https://www.joeydunlopfoundation.com/

hope that helps.
maybe I'll look into it too!