Help! What dehumidifier do I need?!

I live in a one-bed ground floor flat. It's in an old house converted into flats so the rooms are a good size with really high ceilings. This is my first winter in the flat and I think I need a dehumidifier but am clueless as to what to get.

I get a lot of condensation on the windows in most of the rooms.
The humidity ranges from the high 60s up to the lower 80s.
The bedroom is also incredibly cold with, what I have been told, seasonal damp on one wall.
I have also noticed that my clothes/towels smell can smell weird (not a musky smell I have found before when putting washing away that isn't fully dry, but a weird smell I can't describe and not on freshly-washed clothes rather on clothes that have been hanging up for a bit).

I do not have the heating on often due to a mix of not being at home that much and because of the cost (I can't control the heating when not in, so don't want to run it all day when I am not in).
The coldest part of the bedroom can already be as low as 8 degrees in the morning (no clue how cold it gets in the night). Even with the heating on the bedroom doesn't really warm (only one small radiator inbetween two drafty old sash windows, which have broken secondary glazing which I will get fixed).

I think I need a decent sized dehumidifier due to the high ceilings? Would a 20L be enough?

If I get a compressor (cheaper to run?) and run it in the warmer rooms will this still help the cold bedroom?
Or do I need a desiccant?
And would one with an air filter be good for my clothes problem?

I have seen lots of great things said about Meaco but still get confused as to which model would be best for me.

Any help would be greatly appreciated!

Adding further details:
I open the windows every day that I can (as ground floor only open them when I am in, so there is the odd day here and then when I don't).
Always open the bathroom window during and after showering until condensation has well gone.