Hi! Take a look at Marathon watches or CWC. Both brands have mechanical and quartz movements available. I like those brands cause they offer rough, military style watches that can take a beating and are waterproof. I think you can find a great watch for £500 with these brands… And dont underestimate Seiko! There Seiko 5 line and divewatches are near bulletproof, high quality and very good price! Also possible for max £500 :)
Hope this helps! Please let me know your choice! :)
All the best!