Vauxhall Astra i get a smell (oil?) when i first start the car and it goes away after a while.

Excessive engine oil level , if not just minor , can cause it and other faults if oil pressure builds up . You want to check the engine is breathing o.k with crankcase breather operation and no leaks or blockages on hose .

Thanks. I think it is a breather problem. I will get it checked out. asap.