It's a bit too late I would think to organise camping near Whitby for the fringe of the Moor and coast weekend but how about these as fee or nearly free!
11 -13 the May, Alwinton near Rothbury, Northumberland, at Clenall Hall, £10 for camping and I'm running a Saturday afternoon session themed on Lust and Depravity!!
19th May York day of Folk
26th May Norwell Happening
8th - 10th Robin hoods Bay Free apart from camping I think or Blaydon £25 per ticket - no conc. for unwaged but not a bad price for a weekend
15 - 17th Beverley fringe free but camping hard to find
22nd - 24th June Croxdale Traditional Music, Durham, £10 per van for camping
Thursday 19th until 23rd July Staithes Weekend £22 camping for the 4 nights
Durham Folk Party 27 - 29th July cost about £10 per person including camping I think
10th - 12th August Yorkshire Traditional voices weekend about £12 per ticket including camping
And then Whitby fringe!
Hope I have helped a bit - if you know of any others could you please let me know?