In reply to Steve Dunne:
1 Get some experience/ do some voluntary work. Doesn't need to be with a prospective employer (though it helps to be known) but some sign that you've got some committment is very important on the CV.
2 For most it's a vocation not a job. This isn't neccessarily healthy, but it tends to be true. Why the career change? Do you like being outside? - that's probably not going to be enough. do you have a longstanding interest in birds/ moths/ dragonflies? - that might be more help
3. Mostly it's about selling stuff - be it gift shop tat or ideas or the latest campaign about meadows. You'll also be the face at the front for litter/ dog mess/ badger culling/ the fact that someone from the council didn't fix Aunty Bessies kitchen once.
4. All the exciting jobs are done by volunteers or contractors. Mostly you'll be applying for grants for other people to spend.
5 Still interested? Get a qualification. A lot of places do part time FE courses, or better yet, a degree. It's a ridiculously over qualified sector.
6 Long hours and low pay are still the norm. Though it's better than it used to be.
7 Public or voluntary sector? Vol sector is often more demanding/ difficult to get started but the work is more interesting and the sites are better (usually) Public sector has lots of pay/ recruitment freezes at the moment. Conservation budgets get cut first
Very rewarding area to work in (not withstanding the above!) but still very competetive.