Some observations:
First of all, British lasts and American lasts are not the same, consequently, you may find that you generally get a better fit with one than the other. Personally, my feet tend to get a better fit in British shoes or boots more than in American ones, but not always.
Second, buy you boots large enough to wear two pair of socks. A thin inner sock, silk or polyproplene, and a heavy pure wool outersock. If you haven't done this combo, you will be very pleasantly surprised with the results. You will never get a blister or a "hot" spot.
Like the earlier poster, I once had a pair of Redwings that lasted me over 20 years and were in relatively good shape when i tossed them into the bin. They are going to run about 120.00 U.S to 160.00 U.S.
As for Lightweights, you can't beat the Browning Lightweight. Made out of Kangroo skin and they are extremely light. They wear like iron and do not fall apart. No, They probably wont last as long as some real heavy duty boot. But, to me the trade off is well worth it.
To the person that had a problem with one of their big toes, here is a suggestion. Here in the U.S., and I have no reason to think it would be different in the U.K., you can go to the stores that specialize in items for invalids, handicapped, et. cetera. They oftentimes will handle shoes and boots made for people who have diabetes. The only difference in these shoes is there is more room for the toes. The boots that I have seen look quite nice and appear rugged enough for any type of walking, hunting or whatever. I haven't used them but I have a relative who has and they are quite satisfied.