Hi Mick
Steer well clear of Autoglass mate (unless your insurance covers their full cost - but I don't know what the service is like), they are very expensive, iirc around £900. That said it would be for a genuine Nissan screen, however you don't really need to end up with that. The ones that are manufactured from other companies are perfectly up to it (although some people strongly disagree) and are significantly cheaper.
My insurance policy only covers upto £350 for a screen with a £60 excess and the company I've used really are fantastic, although they are a long way from you I'm pretty sure they're part of a network so would be able to recommend someone for you - may be worth giving them a bell anyway its:
Bolton Safety Glass
97-99 Derby Street
Bolton, BL3 6HH
01204 393260
Good luck