Internal insulation - which way should I go - conflicting information

Hello guys ,

I don’t know which way to go with internal insulation .

Here is some pictures of the inside of my house.

What are the possible methods I could about insulating my home internally. The floor space is about 45 square meters downstairs . Saving space is a must. EWI is not an option.

There’s a lot of information out there but I don’t know what’s right for me.

The house is built in 1948 and poured concrete.

Few points

I won’t be removing the stairs and they are on an external wall. I have to be careful here with Insulation as they will make the stairs to narrow.

The joists run along the front and back wall and they are basically on the wall with no way to get any insulation between them and the wall.

Any help would be great . Or a point in the right direction .