Your motor sounds far too nice to scrap Glenn! PLUS, at 66k it's only just run in!...with the added benefit that you already know the car. Buying a 'new' one for £1200 will inevitably mean you will be spending more money on it and a whole load of other unknowns, at least you know the history of your car.
£95 an hour labour at Vauxhall!?! It must be a very prestigious dealership employing mechanics in Versace overalls! Our local VX is around £45 an hour labour.
I know some members on here buy vehicles specifically with oil cooler failure to fix up and sell on. Looking at that diagram mate, it's got to be worth a go yourself! After all, it's not going anwhere at the moment so you still have to dispose of it meaning hire of trailer/recovery and a load of paperwork which obviously takes time, time better spent having a go at fixing.
....and when you get stuck, post up a thread here and ask some questions, there's no such thing as a stupid question and guaranteed somebody else will be asking the same! To which, the knowledgeable guys on here i'm sure will have the answers.
Good luck
