So many possibilities!
Here's one:
Drive to Wasdale Head, cheap camping opposite hotel, free parking just down the road. Enjoy Ritsons Bar.
Day 1 am - Scafell Pike, Ill Crag, Broad Crag, Esk Hause, Angle Tarn, then down to Langdale for a well earned pint (choice of pubs)
Day 1 pm - walk down valley and across low ridge to Grasmere, then up to Grisedale Tarn south of Helvellyn (wild camp).
Day 2 am - northwards to Helvellyn and then down to Thirlspot for a pint in the King's Head.
Day 2 pm - around the top of Thirlmere (permissive paths) then over the hill to Watendlath Tarn, then to Rosthwaite, Borrowdale before climbing up westwards to small tarn between High Spy and Dale Head (wild camp)
Day 3 am - over Dale Head, Hindscarth, Robinson to Buttermere (pub)
Day 3 pm - Along west shore of Buttermere, Haystacks, Brandreth, Green Gable, Great Gable before descending back to Wasdale Head.
I haven't camped at either of the wild camping spots mentioned, but I imagine there would be some good pitches in the vicinity.