Does anybody know of courses in the Bristol area for a dog grooming?

I would suggest you travel along the M4 to Swindon  It'll be money well spent. :)
http://www.charneykennels.co.uk/courses.htm

These are the people I was going to train with when I initially wanted to learn how to groom a few years ago.

Although I didn't end up using them (travelling distance too far in the end), Lesley (the owner/) was extremely helpful and she came highly recommended.

http://www.caninedesign.co.uk/home.htm