Geography Work ExperienceWatch
In terms of where to look, a good first port of call is seeing if there are any family friends who work for organisations that are geography-related, e.g. environmental consultancy, city planning, conservation, GIS, etc. Definitely have a look at the resources that the Royal Geographical Society has - I'm not sure if they actually offer work experience, but in terms of the career and exploration-related resources they have, they are genuinely outstanding. If there are any local universities, maybe send an email to the undergraduate tutor/someone who looks friendly and ask if you can do a work shadowing placement or something like that (I did that at UCL and it was good fun).