I used to organise lessons there for Durham Uni and occasionally helped out with the yard work when I had a free day.
The instructors are lovely and so are the horses, there's an indoor and outdoor school, cross country course and plenty of hacking.
Not sure of livery prices as never kept a horse there but lessons were about the standard price for that area of the country I think (we got a special deal with us being from the uni so not 100% sure what they charge 'normal' people).
I had an amazing time when I was there, I miss it lots, and the fabulous pony I used to ride. If Pepsi's still there give him a cuddle for me