Check if you need a pump or if your exisiting one is up to the job!
Having explored all the DIY stores and read various guides, which I would advise anyone to do, I settled on a Steam Room/Shower and duly'won' one. Extremely happy with price and delivery, although seller not too knowledgable and the installion guide was a little 'sketchy', but I was nevertheless pleased with my bargain.
Had a plumber to visit, CORGI registered with a Part P, as advised. The one thing that I hadn't taken into account was a pump. I was given a pump spec of a min of 2 bar twin, I can't remember if it was a 'positive' or 'negative' head. My plumbers quote for buying one, even with his contacts was £400+ for the pump, so he suggested I look online.
After looking at the ones suggested, his pricing was correct, I duly purchased the pump online, a lot less than my plumber could. The word of caution here is DO check before bidding/buying if it comes with a pump. If not, ask what type of pump is required and check out the pump prices first.