My jazz knowledge is terrible but id like to try learning a jazz piece for solo piano. Im about grd6 classical and would be interested in a piece with a catchy melody. Any suggestions?

I reccomend the music from the film "The Firm" by Dave Grusin. The piano solo book is great fun to play, and probably around your level

Try Christopher Norton's "Microjazz" series, or some of the more advanced of Pam Wedgwood's "Jazzin' About" series - I think "More Jazzin' About" is about Grade 5 level.

John Kember 'The Jazz Piano Master' Grade 6 +

ABRSM Grade 1- 5 books are usefull.

After hours jazz - well know pieces arranged by Pam Wedgewood and some new pieces written by her.

How about Brian Bonsor. I've played a couple of his pieces in ABRSM exams (at grades 6/7). It might be worth trying to find the book "Jazzy Piano no. 2" where the pieces were taken from.