Like I have said in the link, it is possible but you will need to remove the inner wheel arch plastic protectors. Why go to 17"'s when 16"'s will fit no problem with 205/45/16 tyres on.
as long as you us extra low profile tyres shouldnt be a problem. speek to a performance tyre specialist for tyre size. ats and kwik fit dont now anything like this as they are no older than 17. But they might tell you of a good acne treatment.
You can go as low a 40 profile but I would not go any lower than this because it will upset the ride quality of your car and even at 40 profile you will feel every bump.
Wheel arches arn't as deep on the Mk2s, so like meganecab says not unless your prepared to mess around with the wheels arches or the rubber on your wheels
1. Easy to fit
2. Will handled better
3. Will not scrub
4. Will not destroy ball joints
Alternatively sell it and get a 172 ( prices are very good at the moment and if you can't afford to insure it then found out how much declaring your 17" wheel modification to your insurer will cost you before you have accident )