In reply to John Ww:
I've moved house, moved job and moved country in the last few weeks, not to mention exiting a long term relationship and rejoining my old MRT. So, many apologies that I didn't acknowledge your 7 word comment sooner but my life has been quite busy.
Thanks everyone for your suggestions. I went with Haix Connexis boots in the end and so far they're ace - comfortable, smart, warm and totally waterproof. Now I've got the gear I just need to get some some sort of idea how to do my new job...