This isn’t a straightforward question. I’d say you could move the stair but im not sure if the bathrooms at ground or first would work anymore. But it’s a horrible layout as it is - removing the stair entirely would benefit the plan!
First thing is that you will need accurate measurements rather than the agent’s plan. You need the floor to floor height. And also the dimensions of the rooms at ground and first floor.
then look online for a free stair planning tool which meets Building Regulations part K. You then need to pick a riser (height of one step) and a going (length of one step).
Regs say risers must be in the range 150-220mm and goings 220-300mm. So now you play about with those two things - using the maximum riser of 220mm will get you the steepest stair - which has the fewest steps so is the shortest on plan/takes up least floor space. So you leave more space for bathrooms. But the smallest possible stair is fairly horrible to walk up. So I’d suggest you go with a riser of around 170-180mm and a going of 250mm to make it comfortable.
To get the number of steps you divide the floor to floor height by your chosen riser height. To get the stair length, you multiply the number of steps by the chosen going. With that sorted you can look on the plan to see how it might fit into the space.
if you’re putting the stair where your arrow is, Youll need a stair which turns back in itself to avoid a corridor/landing. Which probably means no first floor bathroom and a low head height ground floor WC? (ETA oops sorry also losing the entrance door?!)
ETA again - you need to check where the 1st floor plan sits above ground floor. These plans aren’t clear and it makes a massive difference