Hello.
There is no difference regarding how to file US taxes, except you have an automatic 2 month extension to June 15. You may also file form 2555 to exclude upto $92,500 of Foreign Earned income, and/or get tax credits for tax paid here in the UK.
You can print off the relevant forms from irs.gov and do it yourself by hand, use Freefile, or buy a program to do it. Alternatively we would be happy to assist you if you'd like it professionally completed, ensuring you are taking advantage of the maximum benefits. Possible. email/PM me if you'd like more help.
IRS CIRCULAR 230 NOTICE:
To ensure compliance with requirements imposed by the United States Internal Revenue Service, we inform you that any tax advice contained in this communication (including any attachments) is not intended or written to be used, and cannot be used, for the purpose of (i) avoiding tax-related penalties or (ii) promoting, marketing or recommending to another party any transaction or matter addressed herein.