I am sure that Ana was able to use Google and find the two main festival lists for herself. What is being asked for is RECOMMENDATIONS. They will all say that they have "sessions" but you need to know the festival to know if that means a solid day singing or a lunchtime of fast and furious irish instrumentals.

Whitby has my vote, for trad performers in concert and instrumental sessions at that time of year I would also suggest the Traditional Music Day in Stowmarket but opportunities for singing are limited.

It is not a fault of fRoots/Spiral Earth or EFDSS if their lists omit a particular festival, it is down to the festival organsiers to submit their listings.