He could also talk to Outward Bound instructors and to his DoE assessors - or the gold trainer, they have to have a higher qualification than the bronze and silver ones, so are more likely to do it for a job, or at least get paid.
Does he want to work in outdoor education (a branch of teaching), at activity camps (like PGL), as a mountain activity instructor (navigation, hill walking, climbing) or in the outdoors (nature reserves, forestry)?
The first and last require degrees (more hands-on conservation jobs are often advertised as degree or equivalent, so could be HND or whatever they are now, plus strong experience). Mountain activity (see the courses at Plas y Brenin) requires you to be extremely good at the activity you want to teach, based on years of practice.
For any of these, voluntary conservation work and summer jobs at activity centres would help. Conservation work will be voluntary but there are plenty of week long residential 'holidays' (BTCV, National Trust) that would be relevant to his DoE and he could go on to lead these, they rely on volunteers with fairly minimal qualifications (first aid, ability to drive a minibus, common sense and an interest, when I led them as a student), which is good experience. A lot of this stuff relies heavily on being able to work with and lead people.