I get that you can have one for a year but then how do I get a permanent one?
You don't actually get a U.K. license for a year; it's just that the law says you can drive on your American license for a year.
But, unfortunately, 13 or 30 years experience counts for nothing, and you'll have to undergo exactly the same range of tests as a 17-year-old Brit just starting out. If you haven't acquired a U.K. license within the year, then you're under the same conditions as a learner.