Stoner,
Your county council should have published the dates on their website. Anyone looking at the easter holidays will find that there is a difference between counties.
OP have fun on your search. We are trying to find a reasonably priced half term or easter ski trip next year for 9 adults and 6 primary school age kids. Balancing snow/facilities/price is all part of the ‘experience’.
Igluski and the Telegraph websites give reasonable/good info on resorts.
Pre child we always went in the first week after new year as it was cheap and the snow was consistently good.