As a Civilian Instructor you would merely contact the local Sqn, they are likely to be very keen to get someone with your background. I should think the only hoop to jump through is filling and waiting for the DBS. With your background I expect there would be opportunity/pressure to be uniformed staff and Wing admin tasks could also be encouraged if that’s your thing.
(and thanks to all those ATC CIs and officers who gave up their time to set me on my way in aviation all those years ago!)