What do I do after A levels?

What do you want to study & where? What languages are you fluent in at a high academic-technical level. If you are only an average student, it is highly unlikely you can compete for admission anywhere as a foreign student.

What's your budget? You must prove you have sufficient funds for all school + living expenses, plus return transportation to your country, to apply for any student visa.

Get a job.

Having relatives abroad will really help.

Try applying to abroad universities online through their websites.

If they accept you and all goes well, at the very end they might send you a visa.

But I must warn you that the competition can be very tough.

Go to the website of the embassy (of the country you're interested in). Or visit the embassy (e.g. the UK embassy) nearest to you. They'll walk you through it.

you would go to the UK provably
the US has no idea what an
A level is

What subjects did you do? What countries do you want to go to? How good are your English and other language skills? You probably need to give more information and talk to your college about applying to study abroad.