Having taken it to a non-dealer it appeared to be a "fuel pressure sensor" having an intermittent fault - according to the VAG-COM readout. However they can't get a new sensor (£30-40) until 4th April!
So reluctantly i took it to the local main audi dealer, and £99 +VAT for 1hrs work later they told me it'll be £526 for a new Fuel Pump, Fuel Sensor, Hose and Filter, including 2.5 hrs labour to fit it all!!
I was shocked considering the garage the day before said it was just the sensor. Luckily i was recommended a third garage by a friend thats recently been set up by 3 ex Audi mechanics so i gave them a call - they still know the guys at the main dealer where my car is so they called to get a run down on audi's prognosis.
Turns out there's a Technical Bulletin for this issue on A3's and the technical bulletin states that all the parts i listed above should be changed. The guys at the new garage say if i'm lucky it'll just be a the fuel pump, and i wont need a new sensor, filters etc.... and they charge 1/3 of Audi's hourly rate so i should save myself a bit!
So its going there tomorrow and i'll let you know how i get on. They did point out that it might need all the work audi suggests, and more worringly it could need extra if it is a blocked pump and some of the blockage has made it through the two filters into the injectors in the engine - i really hope not!!