I would agree with the recomendations to go to a good outdoors shop, do not buy something off the net which you have not tried.
I generally go to cotswold outdoors, they will fully measure your feet both loaded (i.e. standing) and unloaded, you will be suprised the difference, my feet are a size bigger when I am standing than seated and two sizes wider.........
They will really do a fully comprehensive fitting service and if you are not hapy after a couple of weeks you can take them back and they will do more, add insoles, heel lifts, etc until they are perfect.
I had a pair of Meindl boots which lasted me 12 years, fishing and hill walking and last year got a pair of the Scarpa GTX which are goretex lined and very, very comfortable.
What I did find when I bought the Scarpa's is that different makes or styles of boots suit different foot shapes so you really need to see what is good for you, any recomendation might not suit your foot shape.......I really wanted another pair of Meindl as I considered them the best but there were non in the current range which were comfortable with my wide feet......
Footwear is the most important pice of "tackle" you will buy, especially if you walk a lot and want to stay dry and warm..............buy wisely