TAKE IT. I am also in the AF, and I just had a good friend of mine go to england. The thing is, the AF won't pay for you to ship a car back to the US unless you take one over there with you. So even if you take it over there and sell it (and I bet you'd get good money for it), at least when you come back you can bring whatever you have over here with you.
Also, as far as gas is concerned, my friend says if you get it on base, it's only $2.50 a gal, but outside of base it's like 85 pence a liter or something,
Also, a little heads up. My friend had a 2005 Jetta, and he had some problems licensing his car over there. Apparently, you have to have a 'rear fog light', your turn signals HAVE to be amber, and they cannot interfere with the brakelights (ie, they have to be their own element, they cannot just be the brakelight blinking).
Edit: The inspection is very strict over there, I don't know what kind of shape your car is in, but it'll probably be a b*tch if it's not in good shape. I hear they're anal about body damage and stuff, as well as emissions. If you have any specific questions, let me know and I'll call my friend.