Work Z visa multiple entry

I will be teaching English in China from September 2014 - June 15 and I am permitted one month holiday from January until February - in this case I would like to travel outside of China (perhaps back to the UK). My employer is organising it for me soon, do I have to state to them I would like multiple entry option (if it is even available for this type) or is this something I would have to organise personally when I am in China?
I hope someone can help.