Merlin powerstore (google it) are in Poole, but will post. Sell good stuff, not always the cheapest. furneaux Riddell are near portsmouth, just off the A27
We used Barden. They are so very helpful, give excellent after sales service and are extremely knowledgeable (and just down the road) /forums/images/graemlins/grin.gif
Barden in Segensworth, used them for Motorbike batts, because I wanted a decent make like Exide.
Segensworth is just off the M27, but a nightmare for rush ohour traffic!
Tayna- Google them on the web.
I have just bought two of their Elecsol 110 AmpHour models for a very reasonable price even including carriage. They are reinforced with carbon fibre to prevent damage when deep discharged. Come with a 5 year guarantee and arrived in a couple of days.
I chose these because they are the only ones apart from Varta (at twice the price) who make batteries low enough in height to go below the aft cabin bunk.
Barden stock a good range, but are VERY expensive - the Squadron AGM's I have came from them at a tad under 150 quid each, found the same thing later ( as you do) on a caravan site at 80 quid each.