Another thing to consider is a normal Golf can't have just GTI suspension fitted as the shocks are a different width so you'll need to fit new hubs too which is a big job. Get something small engined and reliable for a year or so while you save up, I know you'll hear that all the time but it comes from people who were once where you were.
Also, for insurance, don't bother with the usual comparison sites, get onto the phone and give either HIC, Greenlight, Sky Insurance or Adrian Flux a call, they're proper brokers who'll get you a much better policy and price.