I would stay well away from a Golf GTI of that age, the bets are that it's been ragged and Golfs of that age were known to be very unreliable, i would not pay that ridiculous price on insurance on something that is probably going to cost you a hell of a lot in repairs. If you want a 1.8 i would go for a Focus, it may got be a GTI but if you start hammering a 1989 car it is going to blow, very reliable and insurance is not bad. Or wait a few years and get yourself a civic type R, had one few weeks back before some1 hit me and writ it off, Lotus exige for next car
any rust in the engine bay it's a big no no, and the insurance you said that is a silly price to pay for it, i know you stated you have only been driving a year.... but still i could get insured on a brand new skyline for that.
But if your heart is set on it everyone has their own opinions on cars, i realized that when i see so many smart cars around! Anyway if you need any advise on it m8 i can help out a lot, can tell you exactly what you will need to check on the car, the spots where it may problems but not yet indentified. Nothing worse than buying a car and having the valves jump out due to a faulty fan belt, then costing you £600 to repair, or realize after a few weeks that the tracking is out, unfortunatly cars can look good on the exterior but id rather have a car look crap on the outside and perfect under the hood, cost a lot less to repair.