The best place I have found to buy a wetsuit is the new shop down in Yeovil at TRIUK as you can test it out in their indoor swimming pool. It's a long way to go but worth it to get the right suit, failing that most places will let you take it back if you only use it once. Then failing that there is Total Fitness in Nottingham, or Terrapin is the most local supplier.

A few points to bear in mind when buying a suit.

Its important with wetsuits to get a really good fit, tight but not so much that it restricts your breathing or shoulders. try different makes of suit as some fit better than others depending on your body type etc. Talk to the shop staff and they should be able to help you out and offer advice on all the various models.
Make sure when you have got it on that it fits up into your crotch and under your arms snug.
I'm tall 6ft 2 I find that wetsuits do come up a little short on the arms and legs. The best suit for me is the Ironman range which is what I use now.
I first used a Orca Predator but I found it a bit restrictive and even shorter on the arms and legs.
There is a bit of an art to getting the suit on and be careful with your nails as you can split them easily if you're not careful. Try to ease the suit on using your finger pads NOT your nails.
Remember don't rush - get your suit on right it's the taking it off in transition that's important.
Before you swim use either baby oil or similar around your neck as it can rub your skin raw without it. You can use Vaseline but wash your suit well after as it can rot your suit after a while.
 

Open Water Swimming
Whenever anyone is thinking of starting some open water swimming for the first time then let the club know, we can do an awful lot to make things less daunting.

Club members attend Open Water swimming on Saturday mornings at Market Bosworth Water Trust starting late April/early May. People start arriving for the early morning dip from about 7:00am onwards. There is a £3 barrier entry fee to enter the site. IMPORTANT - Please take time to read the notices posted in the changing areas to ensure our continued use of this excellent facility.

If you have a 'thick' swim hat or better still a neoprene swim hat it is advisable to use it at the sessions in April/May, it takes a few weeks for the water to warm up!! Be prepared for an initial shock when getting into the water & give your body time to adjust, within a few minutes of being in the water your body will adjust to the temperature & the thin layer of water between your body & your wetsuit will have warmed up to body temperature to make things feel a little bit more comfortable. The next shock will be when you start swimming & submerge your head, you can get a similar feeling to when you eat too much ice cream ('brain freeze') across your forehead or the crown of your head. If you find it a bit too scary then swim with your head up to start with but once again in a few minutes your head should become accustomed to the temperature.

Make sure you bring warm clothes for afterwards, for anyone who has never been before there are warm showers available. On some of those chilly mornings it can be worth taking a flask although the cafe opens at 9:30am serving hot drinks and bacon