These are not too near your area but you might as well ask them for some brochures and get the widest choice possible. Try:

Brent-Wood Burners
3-5 Coxtie Green Road
Pilgrims Hatch
Brentwood, Essex
Tel: 01277 374247

Essex Stoves
Black Notley
Braintree, Essex
Tel: 01376 331731

Litton Brothers
Estate Yard
Ockendon Road
North Ockendon
Upminster, Essex
Tel: 01708 220433