A few people have recommended West Essex Saddlery to me recently.
Or Ingatestone has a good range of saddles, I've no experience of them as fitters though.
I've just got a made to measure saddle from mill saddlery, I used Liz they are brilliant, & never had a better fitting saddle, they are in Suffolk but come to Essex.
I got a made to measure ideal Jessica saddle from minster saddlery in kent. They travelled to me in Essex (Chelmsford) for £30. I have also used Martin wilkinson to check saddles and my friend had a jumping saddle from him. he was very helpful