I don't know of any websites other than the ones you mention; oh there is this:
http://www.photographers.co.uk.
13 years ago I wanted to assist television cameramen in the region I lived. I found out where they were based (this was through the 'Eastern Screen Handbook' at the time, now on-line) and wrote them a letter. Out of about 20 cameramen most of them responded favourably and I got assisting work from 2 which eventually became paid. Contact individual photographers and ask them to do work experience or 'shadowing' for a few days. You may find that there aren't any landscape photographers in your area so be prepared to travel and give up some free time.
How about contacting the local paper, their photographers could be freelance and do other work as well as photojournalism? There are a few photographers and studios near where I live which I didn't know existed till I did some research.
Good luck.