Thanks for the replies everyone.
I'm inclined to think it's not the box itself having talked to a few other people. The gears usually go in quietly, it's like something isn't lined up properly etc so the linkage guess if probably a pretty good one.
Somebody said it might be worth getting a "GEAR LEVER REPAIR KIT" from GSF which is basically the plastic ball that sits at the bottom of your gear stick. I'll give that a try as it was only £5 and if that doesn't work I'll put some effort into other fixes.
I agree that £800 does seem excessive and I'm not really inclined to pay that kind of price, however, the car is in really good condition and has only done 60K I'd rather not sell it as everything else seems to be in good working order at the moment(touch wood).
Regarding the brakes, I'll probably just go standard I've already got a quote from Stu at Euro Car Parts in leeds, totalling about £120, it's considerably less than the £500 that same garage quoted me. I only take my car to that garage in emercencies, anything else I can do myslf or take elsewhere I do.
I'll let you all know how I get on.
Cheers guys