US qualifications for UK jobs

I am a US/UK citizen who has recently moved from the States to Edinburgh. Currently I am working in the IT field, but I am planning to change careers to something working with environmental science in a few years. I am halfway finished with a BS Environmental Science degree from Oregon State University. Therefore my question is how other US expats have experienced applying for science/engineering jobs in the UK with their US degrees. Especially those who are working in the environmental science /ecology fields. I am hoping to complete a few hands on certificates from the likes of the Royal Botanical Garden Edinburgh to compliment my final degree and also try to join some local societies. Any advise is welcome.

I haven't had any experience with that myself, but you might find this useful:

http://ecctis.co.uk/naric/Individuals/Compare%20Qualifications/Statement%20of%20Comparability.aspx

It's a government-backed service that gives you a certificate saying what your US qualifications are equivalent to in the UK, which you can then show to an employer.

I'd be looking at the professional bodies and courses related to your engineering specialism. You can start by looking here (also provides a search engine for postgrad study):

http://www.prospects.ac.uk/types_of_jobs_engineering.htm