Thanks all for your help. To answer a few questions and add some clarity.

It is a petrol Audi A4 s-line 1.8 turbo which has done 125k miles so likely the engine is a bit worn. It had always used oil but not to the current extent. Besides the cost there is always the hassle of constantly topping it up. When the oil pressure sensor detects you have forgotten to top it up and you are in the middle of nowhere and you realise you forgot to top up the spare can in the boot. All a bit of a PITA.