Pre reqs??

Yes. A 4 year program is everything from day 1 to graduation. You typically will start as "pre nursing" then apply to the nursing courses midway through the program.

What is A level education?

In applying to a traditional 4 year BSN the first two years of study are typically devoted to taking pre-req courses and general education credits with the last two years focused on nursing study. Some programs incorporate nursing specific courses earlier in the study, it depends on the school.

It is also possible to enroll in a community college or technical college to take pre-req coursework and then transfer that course work to a 4-year school, transferring in as a upper-class student immediately starting the nursing program. As CC programs are typically much more affordable this can be a good way to get credits out of the way for less cost.

At the 4-year university I attended A-level course work (with copy of certificate) could be used to satisfy up to 45-credits (1 year) of study, usually applied towards general education requirements. How they are applied and whether this coursework will count as general education or fulfilling pre-reqs or both is going to be university specific and may also depend on which A-level courses you completed and how well you scored on the exams.

Since you have some pretty specific questions about being an older student, international student (are you on a visa or U.S. resident? - this may affect enrollment status and cost of coursework, as well as eligibility to even apply), transferring A-level credit and so on for nursing, I would encourage you to speak to admissions advisers at the programs you are interested in. You do NOT have to be an enrolled student to speak to an admissions adviser and they will be able to directly evaluate your situation as it applies to their college or university program.

Taking a year off may or may not benefit you. Doing something constructive with the year will make you more appealing a candidate than sitting around doing nothing. Work for a year (if your visa/residency status allows) and save up some money, volunteer in healthcare for more exposure, or take a gap-year and travel, depending on what your credits might do you may take part-time classes at a Community college to get coursework out of the way and establish a track record of academic performance in the American educational system.