People from the UK: need help finding computer parts shops

[Spazatao]

So, my cousin lives abroad working for an oil company that, before letting him enter in vacation, decided he needed to go to their office in Scotland and do something there. So, he'll be there until this friday and then rents a car and goes all the way down to London, stopping for tourism in some cities... The thing is, he offered me to bring some computer stuff that I might want, as those things are extremely expensive here, due to taxation.

So, what I need to know is: are there any major computer parts shops/stores? If yes, what's theirs' website? If not, what would be your suggestions for me to have an idea of how the prices in UK are, so I can calculate if it's worth bringing something?

Thanks a lot guys!