I have just bought a Carrera Kraken from Halfords. For the money its an awsome bike, SRAM X5 27 speed gearing, sr suntour xcr forks, cracking hydraulic breaks andlooks nice too. Use d to have a GT Agressor xc3 till last week and that was a good bike but for mr the kraken feels a better bike.
http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_518229_langId_-1_categoryId_165499
If your after something that will be abused then go for the carrera banshee if you can push your budget.
http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_518221_categoryId_165499_langId_-1?cm_vc=IOV4PLPZ1
Or failing that or any advice from the guys on here try this site and they will answer any question you may have and give good advice on your purchase. There are also some very good bargains in the classifieds.
http://www.mtbe.co.uk/sid=8b96accee16794b748836d3f556e1196
Hope this helps matey.
Daz Cox