I've not used that firm but I wouldn't touch them with the proverbial bargepole.
All UK web traders are legally obliged to ensure that they provide an address for returns. There is no such address on that website. It's just possible that they might leave the provision of their postal address until the point where you get confirmation of your order but that seems to be unlikely. (Trying to access their order page shows that the site doesn't have a valid security certificate. That, in itself, is a worrying sign; the problem shouldn't occur on the website of a reputable firm).
The website lacks the 'professional touch' that I'd expect from a trustworthy company. (There are no 'terms of business', etc).
The domain name is registered to GoGoDigital Ltd, which is described in the registration as a 'public limited company', which appears to suggest that the firm is big enough to have been 'floated' on the stock market:
http://tinyurl.com/2bln74h
However the Companies House website shows that it's only a private limited company (which might well be a one-man operation):
http://tinyurl.com/2bjk2vx
At least the address matches on those two sites, but Google Street View shows that it's just an unimpressive terraced house.
Chris