the problem is, a 19 year old male has problems insuring a car with an added spoiler, ally wheels etc, let alone a bigger engine
these 1.0,s can go well (mine,s certainly not slow) with 1.3 cams and exhaust and inlet mods
best thing to do is get all the parts i.e manifold etc and put them on the 1.0 (so then you will have a fast insurable 1.0 for now)...then when your insurance goes down put in a 1.3 and take all the bits off the 1.0 then you will have a fast 1.3. and all round quick car.
That sounds like the best option. You could even put the 1.3 cams in to the 1.0 litre. It's a very good modification. You SHOULD tell your insurance company if you do this. As it is an engine modification.