You are right, it can be difficult in certain properties. And I can't see a perfect location in yours either.
The hall or landing doesn't have a radiator in, so is not suitable. If the doors into it were closed it wouldn't be able to detect any temperature rise when the radiators came on and the rest of the property was warm. Conversely, internal rooms often don't loose their heat as quickly as external rooms with windows, and if that was the case it may not turn the heating on when the other rooms had cooled down.
I think you have two choices. First, I would tend to agree with
@Mottie.
On the inner wall in the lounge in line with the dividing wall between the kitchen and bathroom.
Although, if the kitchen gets hot when there's cooking in progress and the wall between it and the lounge isn't insulated, I might move it so that it's on the bathroom side slightly.
However, it's even worse if the kitchen is open to the lounge without a door, which your plan suggests it is. In this case cooking would probably heat the lounge as well, thus turning the heating off everywhere. Maybe you could live with this as cooking only tends to be for a short time. No problem though if you don't cook, or live on salad.
The second choice would be one of the bedrooms. However, most people like a cool bedroom so a thermostat in there wouldn't necessarily be representative of the requirements of the living areas, which could then be too cool.
I used to live with my parents in a bungalow with a similar layout and back in the 1980's when I was still at college, I created 5 separate heating zones, one for each room, each with it's own dedicated motorised valve and room thermostat.....probably a bit excessive though looking back now.