Cal, speaking from someone who had a 1.2 engined
Ibiza I can safely say a 15PS upgrade is essentially pointless.
What I do recommend is saving up those pennies and pounds NOT SPEEDING like I did, and avoiding the police.
Keeping that licence clean and in three years buying an FR. Trust me it will be worth it the FR's are alot cheaper on insurance than the cupras and even the diesels pull fantastically.
I sadly got caught speeding twice and had an accident and at 21 my insurance on a 1.9TDI is only £700 I've had a custom exhaust system and a remap and now I'm pushing out 150BHP and an ass load of torque.
Trust me, Set up an account and put £100 a month in it.
You'll come back in three years and be a happier person than if you spend wonga on a 1.4 to get 15ps