If you live in Derbyshire, your Easter 2018 School holidays should allow you to take advantage of a reasonable price at Center Parcs. Derbyshire schools are off w/c 26/3/18, whereas most of the rest of the country isn't off until the end of that week. All of the 5 Parcs are cheaper than the following two weeks, but Elveden seems to be the cheapest. E.g. 2 bed woodland lodge is £429 for a 4 night break from 26/3/18, as opposed to £949 and £899 for the two weeks after. The parks should be a bit quieter too.