Best thing to do would be find a retailer near you - ideally an independent (you can find independents by taking any brand e.g. Britax and looking on their retailer search page) but if no independents near you, John Lewis are good as chains go.
They can then show you different models and you can try things in your car usually.
With a 3 door car you do have the options you've said. I agree a base in the back probably doesn't make sense for you though it is a popular option in your situation.
360 rotation seat in the back -> these can be good. When buying something like this, you'll want to look at where the button to release the spin is placed, and consider how easy this will be to reach while leaning in to the car. Also, just check it will actually spin when installed and doesn't get caught on the side of the car.
You also need to check what protection the model has from stopping you forward facing too early - some of them have a little automatic stopper thing that won't let you turn it forward facing when the headrest is in lower positions for a younger child. Others use a switch or button.
Considering how well the 360 seat fits a newborn will be important too, as some of them are a bit too upright or babies look totally lost in them until they are older/bigger.
Also, they can take up a large amount of space, so definitely worth checking the fit before you buy a seat.
Belted seat on front seat with airbag off > This is a good choice if you are unlikely to have other passengers in the car or if you're happy to let them in through the driver's side.The problem with taking a car seat in and out of the car and having adult passengers in between is that it becomes very easy to forget to switch the airbag on and off. But a permanent or semi-permanent installation is not so bad because you'll just have the airbag off and a lot of parents like this too because you can see the child.
So for a front seat installation you have three options really. An infant carrier without base, an infant carrier with a belted base, (there are a few!) or a multi-stage seat, which lasts up to age 4 or 7 and has newborn capability.
I think in this scenario I'd likely look at Avionaut Sky or Besafe Stretch B. Both of these would be great options and last you a long time and they are really safe seats right up to the age you'd move to a high back booster.
There is a page on Facebook and Instagram called CarSeatSweden which has lots of front seat installations of these seats and seats like them.