I second that, especially if you want an auto.
I’m currently wearing an auto Citizen Promaster diver, in titanium (NY0054 if you’re searching by model number). Not a UK one sadly but there are plenty of sellers on ebay who can send from the far east. Keeps great time, is wearing very well indeed (with plenty of swimming and *gasp* actual dive use) and cost just under £100.
If you like bracelets and chunkier divers watches, you really can’t go wrong with a Seiko Monster – fantastic quality for the price. Again, far east only so off to ebay for one.
Or if you want another option, take a look at Christoper Ward – http://www.christopherward.co.uk/ – british-designed, swiss made. A mate has a C6 diver and it’s very nice indeed. Bit more expensive and quartz-only (auto due soon apparently, for more money of course..) but quality-wise it would hold it’s own against any of the big names at 3-4x the price.