'Nabru' might have something in your price range. Can design your own 'U' and courner sofas too. Might be worth a look. Their showroom is in Uxbridge, I've been considering them but would have to go and check they aren't awful obviously.
I can thoroughly recomend Nabru. The missus and I live in a rented flat where the living room door is, strangely, a few inches narrower than the norm. This meant that the majority of sofas we looked at wouldn't have been able to fit in!
There is a wide range to choose from and being modular in design means that you can add to them if you move to a bigger place/fancy a change etc. So, you could add a few more seats, change the arm style etc. It also means that you can buy new cover fabric which is tailored to your specific sofa - if you get bored of your current colour/texture, you can get a new design/pattern... much cheaper than a whole new sofa!
We paid £40 for the delivery chap to set it up - took him about 30 mins.
+1 from me
