Hiya,
I dont know your whole situation and this is not to alarm you but rather to ask you just to be cautious on your travels to the US. A word of warning - if either of you have any pending visa applications you should beware of travel to the US. That is - if youve sent papers off to INS in the UK or in the US, Immo at your airport of arrival have the power to deny your spouse/fiance entry to the US on the grounds that he may be trying to evade his current application.
Pending applications show intent to stay and settle in the US is there. Although its kind of a counter-logic, seeing as you've sent in the applications and shown that you want to do it the right way, immigration love to play god.
Just be carefull. Make sure if you DO have pending applications, that you take some proof of your return to the UK with you so that you can show Immo that you both have good reason to go back - like job, house, etc. If you can, travel before submitting applications.
I agree with the others about the driving thing - you've GOT to show youre a resident before you can take those tests. Sorry
Best of luck and happy trails,
Sarah