Plywood flooring in small en-suite - gap around edges

[smallsteve1]

I had to remove the original moisture board in my ensuite, and I’m about to replace it with good quality plywood. My question relates to whether it is necessary to leave a 10 mm gap around the small room (< 3m²)? If not, what gap is appropriate? TIA

 

[blup]

Minimum 10mm, gives you 20mm wall towall.

Blup

 

[blup]

Minimum 10mm, gives you 20mm wall to wall.

Blup