I had a Mk3 16v (modern ish with creature comforts) but then changed to a Mk2 16v because it was just a more iconic car and so much more fun to drive.
Yes you will lose some modern features like Air Con (unless you find the one or two Mk2s that have it that are in this country), but if you buy a later H or J plate car you will have options like electric windows, pas, electric mirrors, electric sunroof, very comfy sports seats (perhaps even heated Recaros) and central locking. So A/C is pretty much the only thing you won't get.
I would have a Mk2 now, but my wife doesn't like the "dated" look, don't know what she means
The Mk2 is a classic, the Mk4 isn't and probably never will be.
Keeping the missus happy is important, so just find a very clean Mk2 with at least PAS, CL and Electric windows, then take her out for a drive in the country, and show her how much fun it is (perhaps even let her drive it).
Don't talk about the safety thing, you'll have seatbelts, and because it's lighter, it should be easier to stop in an emergency.
Good luck with that.