If you'd prefer to keep costs low, whilst retaining quality, have a look for some of the
MoD issue Haix boots. I didn't come across these boots in my time in the forces. My introduction to the brand was in the form of some safety boots. I've since bought several pairs of Haix, including the MoD issue boots. For the full leather with Gore-Tex, look for the "Cold Wet Weather" variety. For the leather and textile Gore-Tex version look for the "High Liability" version. Avoid the High Liability suede version, it's an unlined desert boot (though it's still a good boot).
Prices vary depending on supply, but you should be able to pick them up for £65, or less if you are patient (brand new, unissued). Haix do actually retail them to the public, but they are
rather more pricey.