Insulation of property - expert

We had this problem. The EPC report should identify the main areas of concern. Instead of going to find another expert, I think it's better to find someone who will carry out the work for a reasonable cost. In our case, the roof, floor and walls were problematic and the boiler was too old. The boiler was changed quickly and then the walls were the cheapest and easiest to resolve and we had cavity wall insulation installed quite quickly. The roof was much more difficult as the tiles had to come off and this took a long time to organise and sort out. The other problems we are dealing with as and when we can.

What obligations does a landlord have to insulate their properties?
I live in a top floor apartment with no double glazing and the attic above me has no insulation of any kind. What I spend on heating in the winter goes up through the attic instead of efficiently heating just my apartment. In the summer, the problem is reversed.
Does my landlord have an obligation to insulate the attic?