be aware that the saffire only has mic pre's etc and you'd need to use both ports for a stereo sound module like I did.. I did ask the bloke in DV and found out this "issue" later. it's ok. BUT it's limited in expandability wise.
with regard to buying have a look at various pro audio companies in the UK... also buy an asio card..
guitar guitar, gak , absolute , dolphin,dv247, and more..
decide how many in's and outs you need.. yes some cards are more expensive... but think 2+ year on where you will be, so you don't need to rebuy again
maplin's is like US version of tandy/radio shack, they sell components and other bits.. but not the best for pro audio tbh.