Hi sean and a warm welcome to TorqueCars, nice to meet you and it is good that you are already asking for tips and advice.
My brother has a 1.2 Corsa and has been through a couple of idle control valves already! (A common fault on these so look out for it!) Although his is much older than yours.
The 1.2 engine would not cope with a turbo, firstly the compression ratio and power gained would cause detonation issues. Secondly the cost involved in getting a turbo to work would be prohibitive (£3k +) For less money than this you could drop in a more powerful SXI engine.
Sadly though I guess the cost of insurance would be prohibitive whether you modified your car with a turbo or added a bigger engine.
It is hard to say but you are really better off saving your money for you next car and getting something a bit bigger.
If you must do mods to your Corsa then stick to handling mods, brakes and suspension for example. At least the car will be fun to drive and safer.