There are incredibly simple to work on and the FIRE engine has been around since the mid 80's, so there nothing to shock most diyers under the bonnet.
It's also quite a hardy motor and very simple and cheap to service.
A full engine service never cost me much more than £40 or so.( with genuine fiat parts)
Four tyres around £120.
Back Box around £30
Obviously the later cars have things like VVT, extras like Air Con that do complicate a little for the diyer.
I'd perhaps steer clear of the MJ, modern diesels aren't too diy friendly these days, especially common rails which baffle most back street garages as well.
They can also suffer from common, modern diesel problems like turbo wastegates jamming, egr blocking and modern electronic injectors aren't as robust as they should be.
I wouldn't discount the 1.1 Actives.
54hp may not seem much, but it's not lugging around much weight and they are, to me what a little Italian car is all about, small, simple, cheeky, basic, cheap little car that you rag the nuts off and it thanks you for it.
Also, some colours can, after a bit of use and abuse make the car look a bit untidy.
The undercoat is white, so dark colours show up all the chips and nicks.
They do tend to look smarter in the whites, pale yellow and silver for longer.
Another good thing about most of the Actives have plain plastic bumpers, they don't show up all the parking knocks and scraps.
There isn't too much to worry about when testing and viewing.
Check all the dash warning lights work when turning on the ignition.
Check the steering doesn't pull to one side and is smooth.
Back boxes can often look a bit ( or a lot) scabby.
They can sound a bit tappy when cold and oil pressure it low, but it should smooth out as it warms up, (often clean oil sorts this)
The top bushes in the rear shocks can break up and lead to a knock over bumps at the rear, cheap and easy fix.
Check the wear on the front tyres, wishbone bushes can go the same way.
Check under the rear, earlier cars tend to suffer a bit of rust around the rear axle, close to the springs and spring pans, the drain holes in the spring pans get blocked.
Bodies should be pretty rust free though.
Other than that, it's all the usual, used car stuff.