I've forwarded a "sale" advert to your virgin.net email address, you could also have a trawl throught the BSAC (British Sub Aqua Club) forums as people often sell wetsuits and semi-dry suits after completing training/failing to diet ;-)
Google BSAC and you should find it ok.
I use a scubapro 7mm semi-dry suit with a 5mm shorty (with hood) on top for diving because I'm too lazy to use a drysuit, amongst other reasons, and I'm generally as warm with that as the drysuit crowd. It's probably too much for something as energetic as your bodyboarding(!) but imho a 7mm would probably be fine.