Jewlz- Sounds like you are on the right track. I did the same thing as you last year--just worked my way through the IRS publications until I figured out what I was doing. The good news is that once you figure out how to do it, it doesn't take much time going forward unless your circumstances change significantly.
Yes, married filing separately is likely how you will want to file. You can just write 'non-resident alien' in where it asks for your spouse's SS#.
If your income is under the foreign earned income threshold, it won't really benefit you to bother with foreign tax credits from my understanding.
Other things to consider: Do you have interest to report from the US? Do you have UK bank interest to report? This all goes on schedule B. From my understanding, there is no threshold for reporting UK interest, so you have to report it even if it is a small amount. Do you have a UK pension? I don't, so can't really help you there.
If you have not had $10,000 combined in foreign bank accounts at any point during the year, you do not have to file the TD F 90-22.1. You can also check 'no' to the question 'Do you have any foreign bank accounts?' at the bottom of schedule B, since in the fine print it says you only have to check yes if the balance is aggregate balance is greater than $10,000.