Hey Pete, have seen your site before off the Club4AG forums as well as a couple of pics in the Hyper Rev mags. I bet you must have couple of wild meets over there in Ireland.
Unfortunately the police over here aren't too tolerant of burnouts or doughnuts. There's been a thread where ppl here have been pulled over & booked for a doughnut just for losing traction in the wet whilst driving.
As for AE86's, they do have them here but they are the lower spec version - 4AC engine with no LSD. Most get around this by importing parts however for a 20 year old car, they are virtually non-existent these days.
So, unless you get a modified AE86 with the engine converted, you'll have to do the hard yards yourself. Most have problems sourcing a rear diff with LSD of some sorts.
Insurance-wise, I'm only paying $291 AUD for mine however that is only 3rd party property. Been quote around $1,500 for all round comprehensive insurance but I'm a careful driver.