In reply to tinytom:
I bought something like this last year:
http://www.johnlewis.com/lenovo-g50-laptop-intel-core-i7-8gb-ram-1tb-15-6-/...
It is about the cheapest i7 laptop you can buy. It is ok. Nothing fancy, but spec wise it is bang on the money. John Lewis is the only way to go for electricals. 2 years warranty as standard and they will price match.
When you get your laptop, make sure you uninstall all the manufacturers preinstalled software for optimal performance although Lenova do have a nifty backup / restore function which is worth keeping.