Thanks for the feedback so far.
Engine size? Thinking about 1.6 for a diesel, although size is unimportant as long as it fits into the €156 Euro/yr tax band (which the Focus does). Not sure at the minute about the Auris and Golfs in terms of CO2/Kg. The next tax band is €302 so trying to keep the emissions as low as possible.
I am not mad on the Auris shape, but the OH likes it, plus the idea that Toyota will more than likely be more reliable than the Ford.
We currently own an 01 Golf and to be honest they are great cars. Only thing is due to their residual values, we would be getting an 08 Golf v 09s in the other cars, so that is putting us off a Golf slightly.