Different people will offer you different view on hunting knives, as to whether a cheap or expensive one is best...
Basically cheap ones don't bother you as much if you lose one, and allow you to hone your knife sharpening skills without too mush worry of dulling a good knife.
As far as cheap knives go, most people will probably reccomend Frost knives (and I think you can get them with a blaze orange handle so they are harder to misplace).
As for more expensive knives, I would go for either a Cutco drop point with a blaze orange handle, or a Fallkniven F1 or H1 - I personally like the H1 knife, but don't like the sheath it comes with as much as it hangs low from your belt, and so I have an F1 instead.
If you want paid stalking, you could try Greenlee deer in Northumberland (Near Hexham). I don't know anyone in Cumbria, but some other members may be able to help you.
Google the knives and Greenlee and you will find more information on them.
Gez