west essex saddlery at clavering- i think it tends to stock more expensive stuff though so depends on what you are looking for but I have had some good bargains in the past
Over our way you have the Barn Shop just north of Bassingbourn, Sandon saddlery in sandon (an Alladins cave of all sorts of stuff, some should def be on the antiques roadshow (including the owner! who is in her 80's) and Sales of Sandon just round the corner. If you come over to either of the Sandon ones give me a shout as I'm 2 miles away. Although will be in France for a week from tomorrow.
I would recommend West Essex Saddlery at Clavering - they stock a good range of stuff to suit all budgets - I go regularly and have recently bought a new saddle and bridle through them - v good service, their fitter is excellent.