Thanks for all the advice, I was going to cancel, took the car back, they wanted to check it over.
After a 100 mile run and cooled for a few minutes, when they checked the oil level it showed as full.
Took the cover and air filter box off, no signs of leaking, put it on a lift, removed under covers, all looks very clean.
The mechanic thinks it could be smelly air con!
As I love the car, I took the decision to keep it and see how I get on, I have a 3 year warranty after all.
Fingers crossed.