Have a look at Freshman guitars.
I can't remember what mine is exactly, a FA200D or FA250D I think - but they both show up as "under £400". (It might be an FA350D, but that's the next range up - I bought mine three or four years ago though.) I tried loads of guitars in my budget that day (~ £400), including takamines and so on - I'd never heard of Freshman, but the three I tried beat them all hands down (I was after "accoustic only", like you).
I'd second what 38th says as well - have another player with you so you can hear it "out front". Either that, or take someone whose taste in accoustic guitar sounds you can trust!