You could take the fitted kitchen out (or simply remove part of the counter and a wall cabinet) and redesign it so that it will fit a full-size fridge in.
If adapting the current kitchen - either where the draining board is now - swap that for a sink with no draining board, consider installing a draining cupboard above the sink if you don't have a dishwasher, or just get a draining rack with drip tray which you'll have to put away when not in use. Or to the left of the cooker.
You might be able to take the wall out leading to that little cupboard, or take the entire cupboard and kitchen wall out, making it all open-plan, but you'll have to check it's not a supporting wall. Probably just a stud wall with how close it is to the flat boundary wall but just in case.
The first floor plan seems to define an invisible boundary between living room and dining area. Is it possible to place a new stud wall here, perhaps with archway rather than door, and remove kitchen wall entirely, making a larger kitchen-diner?
Is that a serving hatch between the kitchen and cupboard? Perhaps you could just take the cupboard out and have the fridge in the dining area and post things through the hatch!
Also worth considering where the plug sockets are. I wouldn't want to have a fridge plugged into an extension lead, or sharing a socket with anything else. That is generally a bad idea for anything which involves temperature control.
Will it be your flat or will you be renting? Assuming yours, as you're talking about removing walls!