Hi Amy
I'm currently doing the Open University Environmental Studies/Science (don't have to decide which yet

) degree which Hawk Eye mentioned. I'm enjoying it so far but have to say its not very animal/wildlife based I'm afraid.
If you're looking for something a bit more basic then the OU offers a number of short courses on animal related subjects. In the past I've done
S182 Life of Mammals and
S188 Life in the oceans: exploring our Blue Planet, both of which are based around the BBC natural history series of the same names (as a bonus you get several 'free' dvds from the series

). They're only 10 week courses (though you can do them over a longer period) with an online exam at the end and while they are science courses they are pitched at people with limited science backgrounds - though I've got a wee bit of a science background and I still thoroughly enjoyed them. They are mainly science primer courses, teaching you the basics of scientific terms and investigation techniques with lots of wildlife facts and info.
I'm currently doing
S159 neighbourhood nature which is based around the iSpot website and is about giving you the tools and techniques to find, identify and survey the wildlife in your local area building up to a project where you undertake a survey of a species/group of your choice. I technically started in November but have been ill so am only really getting around to starting it now.
These short courses are pretty basic but are actually a lot of fun and you do learn something every time, I use them to fill time between my main OU courses and have enjoyed them all.