to pull it off and get thru the planners you would need to proove you could make money out of it and it wasnt a ruse to get a nice equine property in the country, so you'd need space for at least 15-20 horses... so 20 acres a must.
To built everything you want, and buy the land, you will NOT get much change from £1million in nottighamshire, let alone anywhere near a town or city where people will want the land and have deep pockets to push the price up.
Best bet is to head more remote, up north etc where land is cheap and £500k will get you a house, 20-30 acres of land and a few barns ant a yard, then at least most of the infrastructure is in place.
budget is everything in the equine game.