Just been looking at the Celtic Diving website - they are in Pembrokeshire and make wetsuits, semidries and drysuits. The info on their site seems to imply that they'll make more or less what you want.
Has anyone used their suits? It'd be great to get some comments before investing!
I particularly like the Mr Blobby suit http://www.celticdiving.co.uk/semi-dry.htm 
I rather like the Superman suit. Very colourful.
I was thinking of hiring a boat for exploring the sea caves of West Wales. At £300+ a day I had better get a letter off to Father Christmas straight away.
I've got a 5m dive rib witha 40 horse on it , I'm no diver but love going out on me boat.
I live in west wales too!
You pay the petrol and you could call me Father Christmas if you want.
Serious though any time this summer.
I do know a bit of the coast here but I don't know where the sea caves are.
I do realise your post was from a long time ago but if you still want---
PM me