Hymer caravans

Swifty 123

We have recently purchased a 2007 Hymer Nova and we are really chuffed with it, I was recently talking to a Hymer Nova owner and he informed me that it was permissible to walk on the roof of said caravan ( with care and not wearing clogs of course LoL )
checked my owners manual and could not find reference to it other than roof rack and ladder guidelines, have any Hymer owners come across this, it would be real handy when cleaning etc