Can anyone recommend a fun spot in the Lake District for a play day this sunday, don't want any sort of looped ride, just a nice bit of trail to play on, some jumps and fun stuff to session.

you could go up Walna Scar road and back. Some jump bits on there, and some technical drops.

Whinlatter

Behind castle crag on the Bash would be good, easy access and lots to jump off. Some guys with the DH gear on, were doing just that this Sunday gone.
If you want more techy, you could park at Seathwaite(borrowdale one) ride the couple of km up to stockley bridge. Then carry up the BW, there's some very nice techy stuff up there to play on when you head back down.

Castle Crag is a pretty rocky area from what I remember but maybe worth a look (we're all on hardtails, no squish for us), walna scar could be worth a look though, not often I go that end of the Lakes.

Scratchmere

Walna's just as rocky as Castle crag. 😉

Setters(setmurthy) near cockermouth would tick your boxes I would have thought

Not my vid, but gives you a look at what in there.

starting from where? The Kentmere side of Garburn is just as technical/rocky as the other places mentioned