beetty from the sounds of your set up the door is not the biggest problem in keeping your home warm, but the open plan, 2 radiators and single glazing is probably a bigger problem. Aside from anything else heat rises so the door will have a minimal impact.
Property maintenance is notoriously sketchy when you rent, whether it's from council/housing association/private landlord. Nobody wants to pay out for improvements to something that doesn't directly benefit them. Although I concede there are some stellar private landlords out there who will
The council won't repair just because you keep complaining. They literally don't care. All it will do is flag you as a nuisance tenant and make them take you less seriously when there are issues that they must remedy.
You need to take measures to try and insulate your home for your own benefit. Get draft excluders for your front door (the kind you stick around the door frame), and have a google for ways of improving insulation on single glazed windows. I know cling film is one solution but there are others. Also look at getting reflective materials behind the radiators to encourage heat into your home.
Try and source some heavy curtains too. Closing curtains makes a massive difference to the heat retention in a room.
By all means pursue formal channels to get the council to improve the energy efficiency of your home, check to see if you're eligible for a free boiler upgrade (there are schemes across the country for this) but I'd avoid complaining. Make it more a of mission to improve your surroundings.