If it is the timing belt/chain then the belt kit may well be £50-90 alone.
Then there is the labour to fit it.
How much is the corsa worth to you?
Reason I ask that is that mine just snapped on me while in the outside lane on the motorway.
(Everyone go "Ouch!").
It took out all the valves & has cost me £750 to get repaired.
That on a Renault Megane thats now only worth about £500 according to Parkers guide, but I'd agreed to the work & was committed before I found out the vehicles worth.
Still, all sorted now.
So if the Corsa is not worth a lot then maybe it's better to put the money towards getting a newer (to you) car instead ?