[JonSadler]

Without a related degree (e.g. biology, Environmental Science, Geography etc) it will be difficult to get yourself on a MSc in ecology (or similar programme). An HND or diploma would be a good idea. Have you looked at Continuing Education Courses? Many institutions run these and you might have a better chance there. They are several diplomas in biological recording for example that would give you a route into the environmental field. As has been mentioned here a good few time before what is lacking in this market are good field skills. So volunteering and arming yourself with specialist skills in a group of organisms will certainly help - keep it up. You are probably correct that a diploma might not stack up too well against a Masters but with your strong first (no pun intended) degree, a diploma you'd have a shot, especially with some field survey experience and a taxonomic specialism.

Best of luck.

Jon