Engine noise is not a great issue, it is more tyre and road noise.
So sorry to hear about your good lady wife Jocko, you both have my best wishes. I know how tiring it gets, we have just had the father in law in hospital for 6 months, and even small problems can soon get top side of you.
I took the Jazz for the test this morning, to be honest I find it pretty quiet and refined for what it is. The only problems I have with it is the short suspension travel on these crappy potholed roads around here, and the engine revs at motorway speeds - although it still sounds like a sewing machine at idle, with 167K on the clock.
Some of these modern diesels are very good indeed. I swapped our number one car for a large diesel estate, after driving a petrol Ford Galaxy for many years. According to the fibometer, it's averaging over 56mpg, and the road tax is £30. That's saving me around £1500 a year in fuel and tax over the old bus. It's very comfortable and refined, and just eats the miles up, and with 160bhp, it goes well too.
As for the Honda 2.2 diesel, I think they do have their problems, but they are supposed to drive well. Not the most economical small diesels, 45-50mpg in the Civic apparently. Cracked exhaust manifolds and DMF and clutch problems seem to crop up on a regular basis, as well as some timing chain failures. Make sure the service history is good, and look out for DMF problems - shaking at idle, and rattling on standing revs.
The 1.7 diesel in the older Civic was a bullet-proof Isuzu unit.