Your pursuit is not impossible but it is going to be very tough though. Even with the right qualifications and a straight forward application and getting to your first shift in USA as an international nurse can be a lengthy process with no guarantees that you will even make it. You have to consistent, persistent and determined to reach your goal. If you even have any doubt or you not sure whether this is the right move for you l would suggest you stop now. For every step you take there comes a wait some times half a year.
Ok that out of the way here comes some suggestions about how you can go about the process.
1. There is a new course offered by Kings college that helps with Topping up your original course and also prepares you for NCLEX. It is oversubscribed and pricey but if your goal is to go to the USA that should not put you off. l do not know much about this course but if you join the course it will almost get you to the USA because the people on the course also are dreaming of working in the US. The course has connections with official NCLEX course and some US employers so they can even hook you up with a job in the end.
2. DIY you could choose to do the process yourself and just like people who opt to get direct hires in the US or employment in the US this will be extremely hard and expensive. It is easier to use an Agency to get you to the USA. The DIY option will be more useful for you if you trained under the project 2000 UK nursing training style which meets US standards so in that case your will have done all the 5 areas from pediatrics, maternity, adult, psychiatry etc. If you are fresh out of university l would go with number 1 and do the course.
You might struggle to find Mental health Employers most agencies tend to favour adult type specialities like ICU, OR but am sure there is some thing out there if you dig hard enough.
generally the steps are
1. get a transcript reviewed by CGFNS and a CES report
2. Apply to BON with CES report to hand if you meet requirments you will get ATT to sit NCLEX
3. Pass NCLEX
4. Get employer for green card or marry American citizen
whatever you find easier and quicker.
5. Move to US and live the American dream.
One last word of advice.... No one knows enough about this process to be a pessimist...the rules and opportunities are very dynamic... Good luck!.