There’s regs around how close it can be to water but nothing you can’t work around. Dep on layout you could go nuts and slice off a 70mm wise slither to make a wash room as we did.
Look into bathroom zoning regulations from building control. I expect you'll be fine, but it's harder than you think to comply if the room is on the small side.
Essentially: an electrical socket for a washing machine must be beyond zone 2 which is 0.6m from bath, shower and basin(s).
Can a washing machine be put in a bathroom? Does it need to be a specific type?