Thanks everyone for all the replies. To answer a few questions, I'll be using it for mostly long drives, with a lot less city use. It is the 1.8 MPI though - I don't think the 1750 was ever sold in Ireland. And regarding the warranty, I haven't yet seen the car so I don't know how long it is but it's not a main dealer or anything like that so I would think it will be 6 months max.
Sounds like the general consensus (just about) is to go for the petrol? I have heard that the diesel can be problematic, especially from the DPF. The difference is price is nothing really but the 30,000 difference in mileage is difficult to ignore.
I have the 1.8MPI. Initially engine was quite tight, but has loosened up nicely above 35,000 miles. I get on the combined cycle 36 mpg and on a motorway run with cruise control on 46mpg. Servicing costs are low and do regular oil changes every 6 months and do approx 13,000 miles a year.
I too considered the equivalent diesel, the 1.9 was fairly brisk, but the repair costs at 4 years old or more looked a little scary and with a weak gearbox. The 2.4 diesel on the other hand is powerful and with a better gearbox, but fuel consumption is no different than the 1.8MPI.
Costs of diesel cars at 4, 5, 6 years are not cheap for what needs to be done to them compared to the first 3 years.
All the diesels that I looked at all had leggy mileage at 4 years old, where most petrols have less than half in mileage compared to a diesel.
On the other hand, as already posted is the 2.2 petrol, of which probably is the best compromise in the petrol variants, depending on your budget, but I am happy with 1.8MPI for my needs. I could get a DTM remap, pushing the bhp up another 20bhp, to 160bhp, but happy with what I have got.