Hi Thoma,
If the engine will only run with the choke on then it is demanding more petrol for the amount of air that is being sucked in . Check that the two nuts holding the carb have not worked loose. If they are tight then I would remove the carb to inspect the carb spacer for cracks and the gaskets above and below the spacer for any damage. While the carb is off you can undo the 4 screws on top of the carb to see if there is any build up of muck in the float chamber and whip out the main jet to check it is clear.
I noticed that Redex is half price , £2 , in Tesco this morning and that can help clean out the fuel system.
Many of our 126s have spent time standing which does not seem to be very good for the fuel system. The cars are much happier when they are used regularly.
When the condensor starts to break down it tends to start with misfiring before you get a total loss of spark.