hello, i am afraid that you can not get a visa at border crossing, you will need to visit an embassy to get it done in advance. hope that helps.
We are currently in Cambodia and wish to cross the border to veitnam by land. Is there a Vietnamese embassy in cambodia that we could obtain our Visas from?? We are UK citizens. Thanks
Answer --
Hi Mikka
sure, you can find details of Vietnamese embassy in Cambodia below:
http://www.myvietnamvisa.com/embassy-of-vietnam/cambodia.html