Maybe, but I bought from them (P771ZM, 980m) and mooching around their forums seems to indicate that they dont have an issue with customers opening their laptops to upgrade or repaste etc.. Which could be a large warranty issue if bought from elsewhere. One of the reasons I bought from them.
On a side note, I really think OCUK are missing a trick here. They are in a fantastic position with the size of their customer base to offer custom built and upgradeable laptops just like and possibly even better than what pcs supply...??