Captain two-holds,
To answer your question, I came to the US about 21 years ago to hours build and ended up flight instructing for a few years and then getting an extended visa which enabled me to continue building time including turbo-prop time.
After getting married and applying for a change of status I had to wait about 6 months to get my first work permit. This enabled me to apply for more permanent positions and I ended up flying for a multi-national US corporation with operations in all continents. The actual green card took another 2 years or more to obtain. Still fly for the same company and starting later this year will bring a Gulfstream G650 on line.
If you end up moving to the US because of marriage be prepared to spend several years building time and/or working crummy jobs because unless you have quality turbine time the good jobs are few and far between.
Good luck with whatever you decide.
By the way which part of Wales do you live in ?