Argos can be a good source of decent, cheap acoustic guitars for the beginner. They're of a good enough quality to stay in tune and to enable you to learn the basics, but if the player decides it's not for them, then you haven't spent a small fortune.
Make depends a lot on what sort of style you want to play. I learnt classical for a while and treated myself to a bottom end Rodriguez, which had a good resale value when I packed it in.
Look at Tanglewood, good but affordable and sound nice, and I'm told Vintage (yes, it is a make) is good too.
If you're around Leicester, I can give you the name of a very good guitar shop.