Anywhere specific? There's Cheston at Wrangaton, currently upgrading factilites and sound superb. Also know of a very busy one in South Brent. Umm, Cornwall maybe start at Duchy but very expensive. Could also try going into Cornwall Farmers in Callington and Tuckers in Ashburton and look on their boards.
yes, they have new owners - no longer a riding school. They are upgrading the indoor and building another outdoor school. However, they don't do DIY only part or full livery. I'll PM you a few numbers in you are interested as I was looking in the same area a couple of months ago.