I'm not tax professional, but this is how I did it last year, and everything seemed to be correct. The first thing you should do is visit the IRS website and search for the info packet for residents living abroad. That will tell you everything you need to know, and it's pretty easy to follow the instructions (trust me, I never did my own taxes, even though it would have been easy to do so. I'm afraid of maths.
But honestly, this really is fairly easy to do.)
Basically, you will need your W2's from your jobs in the US. You will fill in the 1040 (not the EZ) as usual with your earnings and any additional money in savings, or support, etc. For what you earned in the UK, you will need to fill in the 2555-EZ for the foreign earned income tax exclusion. However, you have to have been living outside the US for a certain amount of time before you qualify. You are automatically entitled to a two month extension since you live abroad, so technically, your taxes aren't due until June 15th. If you won't be able to meet that requirement of days outside the US by June 15th (again, I don't remember exactly how many days that is) then you will need to file for an extension in order to meet that. But, once you do meet the terms for the foreign earned income tax exclusion, then you fill in the 2555-EZ (so long as you earned less than the equivalent of $91,400 or something like that). You can find the exchange rate they want you to use on the IRS site, and you just figure your income in US dollars using that exchange rate and put that on your form. As far as I know, you don't need any payslips or paperwork verifying what you earned here.
Make sure you actually look through that info packet for taxpayers filing abroad, rather than just going by what I am telling you. Like I said, I'm no professional and I might be missing something out in my basic description. It takes a bit of time to read through it, but it really will help you along to doing it yourself. Good luck!
