Hey Rabi, there's some excellent guitar shops in Tottenham Court Road. When I was there I found 3 shoips in the same street in Tottenham Court Road (although I have no idea what the street or shop names were). For that price range and what you are after, why not try the Epiphone versions of them? I have a vague idea of UK guitar prices and you'll get them under budget. A friend of mine has an Ephiphone Explorer and, given the price, it's a top guitar. Although I'd also rate a Mustang better than an Epiphone Explorer; it's probably also more suited to your style anyway (from what you've said on your post). I played one a few years ago and I thought it to be a good guitar for Grunge & Punk stuff.
yeah there's quite a few, there's two on Rathbone Place which is behind Tottenham Court Road just off Oxford Street. Then there's tonnes on Denmark Street, oppositte Foyles and like you i can't remember the names either lol. To be honest i was playing the Gibson's a few Ibanez's and they just do not impress me as much as that Mustang did but then thats more to do with musical taste than anything.
The places I found could have well been on Rathborne place because the street was just of Oxford. In saying that, i could be very, very wrong. Have you ever tried playing a solid-body Gretsch? I've got a Roc-Jet and it blows the doors of any Gibson I have ever played (well I think so anyway). In saying that tough, I am yet to play a Les Paul and my guitar simultaneously. Tone wise, it's not as full as a Les Paul but not as lifeless as a Strat and with a hint of over-drive, it sounds unbelievably ballsy.