I use a small husband/wife company. They charge £25 for the day, 9.30-4 p.m. (ish) They will have him overnight too for same price. Charge is more for Sun but daughter can have him then. I'm mid Surrey.
Paid £14 per day 7am to 6pm for Poppy to go in kennels for doggy daycare but it is traditional kennels which was fine as she was only in one day a week max for a while.
I'm very lucky - a friend of mine does it for £20/day but does me mates rates at £10/day and only because I insisted I must pay her. We are Cotswolds. To be honest my dog is just one of the family there now, she has him at least twice a week when I'm in London.
We're in oxfordshire, we pay £16 for someone to do an hour's private walk for my 2 which I think is very reasonable. When I looked into daycare it was £18-20 per day per dog, and the person charging £18 had up to 20 dogs.