I want to take my kids away-cheaply?????? please help????

i want to take my 7 year old and 1 year old away in the six weeks holiday thing is they have never been on an airoplane and cant afford that so we have a caravan can any one tell me a cheap site to take the caravan in six weeks holiday in devon derbyshire dales cornwall ect............ thank you so so much for taking your time to read this im desprate for a cheap deal