It's funny you should say you rate the Astra very highly Paul, a good friend of mine is a manager at a car leasing company and drives all sorts of stuff regularly and deals with their problems and sells them again afterwards.
His normal choice, when available, are either Golf GT TDIs or preferably Leon FR TDIs. He never really rates the Astras. Good engine but poor chassis is his usual gripe.
I really liked the GT TDI DSG he had a few weeks ago, but that got crashed by a customer in the snow and he's now in a manual GT TDI.
I've not spent masses of time in his company cars but enough time to get a good feel for them.
Comparing it to TDIs I've personally owned I've got to say it's a very complete package. I've owned quite a few TDIs from the VAG group over the years and to type a mini review of each would take ages so all I'll say is that it feels a bit nicer than the mk5 GT TDI I had. Not as punchy as some of the 1.9TDIs I've owned but far more refined than all of the others put together.
Interestingly I had a bit of a yearning for a new shape Ibiza FR TDI SC at the back end of last year when SEAT first started doing the VAT free offer and my GTI still had a good resale price. I have to say that despite it being the same engine, the Golf feels far more refined, but the Ibiza's chassis was much more fun.