Thanks for the replies!
He wrote for keyboard, i've found a score with his 6 fugues at the British library. Just search their main catalogue at
https://www.bl.uk/. I also know a voluntary he wrote (this one on youtube). I dont have the chance to take the score from the B. Library, and i cant find any other scores...
Im an amateur astronomer and amateur pianist, so Herschel is a great discovery for me

I've found some good recordings too, but that would be great to have the scores.
EDIT: His 8th symphony's sheet is my ultimate wish.
(Sorry for bad english, i really should learn it properly...)