Roundtrip Confusion

Hi,
I am a Uk National wishing to travel to PRC. I have just brought a one way ticket to PRC as i plan on travelling around the country for a month before moving down into Vietnam.

I'm trying to apply for a Tourist Visa but it states i need to provide proof of a roundtrip.

Will A flight or train ticket to Vietnam be ok as a roundtrip as it seems stupid to have to travel back to the UK.