Some friends have been to Caythorpe Court in Lincoln and loved it and some other friends have been to Barton hall in Devon and loved it. Lincoln is a tad closer but we'd be going for a week so Devon would be okay.
My kids have been to 3 different sites. Osmington Bay - fantastic location looking out across the sea. you stay in hi di hi chalets but the family ones have been completely revamped. Liddington - only opened last year and is brand spanking new. no views like ossie bay but modern and up to date accomodation. Boreatton Park - hated it. dirty, very run down and tired, seemed too big and shambolic. Hope this helps