Hiya Greengaard!
Ive recently gone through the process of getting my British husband a US visa so that we can move back to the US. I was resident in the UK when we applied so we did a little thing that most of us here are very familiar with - its called DCF or Direct Counsular Filing. It means that US Citizens resident in the UK can file directly through the US Embassy in London and it makes the whole process a lot simpler and quicker.
Basically the main thing you should keep in mind while you and your husband are applying for a visa to go back to the states is that the forums were written for US based applicants. The forms make it seem like you as a UK resident would not be allowed to sponsor a US citizen which is absolutely 100% NOT the case. You CAN sponsor your husband even though you are not resident in the US right now. The US Embassy in London see cases like yours EVERY DAY all throughout the year and know exactly where youre coming from.
If you have any questions or concerns dont hesitate to ask! There are loads of us who are going through or have gone through the exact same process you will and we're more than happy to lend a hand where we can.
Best of luck on your applications!
Sarah
PS: To get you on your way, the best place to start is with the I-130 Petition for Alien Relative which is filled out by you, the US Citizen.
Make sure you use the US Embassy website that missy mentioned as your first port of call for questions, as the USCIS (BCIS / INS / Whatever) Website does not have great information on people in your situation. Also make sure to send all your forms to the Embassy in London, NOT to the US. GOOD LUCK!!