In reply to Wookster:
I'd write to Terra Nova directly, laying out your experience and passion as you have here.
The average sales rep in the outdoor industry has worked in outdoor centres or climbing walls and usually as a shop assistant/manager previously. The sector is quite small and a lot of jobs will end up going to those who know the sector and the people in it. Do some research into the brands you think you'd like to work for, see if you can get some info on their UK business structure (e.g. agencies, distributors). Outdoori.com is good for job search, but often roles aren't advertised, so be proactive.