My workshop is only 2.4 x 4.2 metres
Geoff,
To some of the members on here, that is enormous.
But as long as you are happy in there, why worry.
It looks to be well organised. That will soon change when you get into metal munching. All of a sudden, the spare bench space disappears.
If you want to attempt to keep the walls clean, I would just pin up a bit of thin polythene behind each machine (even wide cling film), and throw it away when it gets too dirty.
Just enjoy it.
Bogs