Agree with Hobie1. I also owned an Aztec for a while. Great first twin aircraft. Safe, easy to fly and good short field performance (no problem off grass), with great load carrying capacity.
Any twin will be expensive, figure about 200GBP an hour including fixed costs, and this doesnt include any major items going wrong (i.e. engines/props etc).
I can safely say it will be the first (and last) twin I'll ever own. Ownership costs are just too high.