Superhorse the pet shop there is one is Epsom and one just off J8 of the M25 (google it for the address) It depends what you want. Byhurst farm has some tack and bits and pieces and it a few mins from Chessington theme park.
We have absolutely nothing in those areas! Although Im sure if your a polo fan you could call in to the yards in Ham and come away with some bits...
One Stop Tack Shop in East Molesey
Surrey Pet Supplies next to Hersham Station
Ahh I miss having Keith Luxford in Teddington and Millets in Kingston used to do horse stuff
Isn't there a tack shop between Chessington and Leatherhead? That's sort of Kingstonish! Also, there are a few Scats dotted around that have horsey bits in