It looks very likely that I will be working from a single office instead of the UK. As a consequence I lose the company car.
My commute will be 40 miles.
Am I mad?
what should I look out for?
Any one had one?

A cheap old alfa? What could possibly go wrong?

Rust
driveshafts
More rust!

Seriously though, take a look at the 156 section on alfaowner for a good selection of issues...

I don't know about the diesel engine, but my TwinSpark 156 has 187,000 on the clock now.
My commute in it was about 150 miles a day, now it is only 44 which is nothing.
It seems happy at MOT time, cosmetically it still looks good, and it doesn't really let me down.
In fact things like wishbones that fail on the Fiat are stronger on the Alfa. I needlessly replaced mine.
Probably the main criticism is that it doesn't feel like a real Alfa. It is a bit quiet and refined. It has headroom. The pedals aren't offset. The blood curdling scream doesn't really progress through the soundproofing into the cabin. The handling and balance are very neutral.

There is a bit of rust on the bumper hangers, like any fiat/ Alfa.
I sometimes think about replacing it, but I know I'd just want another. It is unbelievably cheap to keep on the road.

I owned one for around a year. Needed welding underneath for an MOT, alternator belt went, and 2 turbo pipes split.

It was okay, quite comfy I guess and did sound good for a diesel being 10v (5-cylinder). Mine was silver though, appallingly dull colour which didn't help. I sold mine for under £2000 with around 140k on the clock.