My friend and I have booked flights into Ho Chi Minh City for the 23rd June, and are planning on travelling up Vietnam, going across to Laos, down to Cambodia and then back to Vietnam for our flight back to the UK mid August. We're slightly unsure about what to do with visas, as we are on a budget but want to be sure that everything runs smoothly - is it best to get a 90 day multi entry visa before we leave, or wait and get a visa on arrival? Also, does the fact that we will only be crossing land borders after our initial flight into Vietnam make a difference? Would there be a possibility of getting a single entry visa initially and then a further visa when we are in Cambodia for re entry, for example, or would this just be extra hassle? Any help would be greatly appreciated!
It's probably better for you to get a multiple-entry visa for Vietnam.
The U.S. State Department makes this observation on its Vietnam travel page:
"If you plan to travel from Vietnam to Laos by land, you should request that your visa be affixed to your passport. Lao immigration requires proof that travelers have departed Vietnam, something that can only be shown with an adhesive visa. Vietnamese officials remove detachable visas from passports when travelers depart Vietnam, leaving travelers with no proof of their Vietnam departure. This situation can result in Lao officials requiring the traveler to return to Vietnam."
Consult your government's travel page on Vietnam. If you're an American, here's the link:
In your case, you should apply for 3 month multiple entry visa. If you travel by air, use visa on arrival. If you cross the border overland, make sure you obtain the visa before departure. Good luck!