In reply to BruceM:
We normally cross on the tunnel (highly recommend) and drive through France, Belgium, Netherlands, Germany and overnight just before Munich (hotel on motorway) and use the same stopover on the return trip. Like in the UK you can save quite a bit on fuel by hoping off the motorways and filling up in local towns, also it's well worth going into Italy with a full tank.
The only toll we had the remotest difficulty with was the Dartford crossing.
Austrian Vignettes are available from petrol and service stations south of Munich (under €10 for 10 days), loads of signs to remind you to get one. Depending on the length of your stay the vignettes are available for different periods, but if just transiting through Austria two 10 day ones are your cheapest option.
Toll for the Brenner pass (under €10) and conventional toll booths so really easy and you will probably also find yourself on the toll motorway when you first come into Italy, it can be avoided but the exit off the Brenner onto local roads is very easy to miss and if heading for Cortina the toll is only around €2-3 and again toll booths.
Never tried going down through France so can't comment.