You are almost certain to see Noi Bai airportduring a trip to Vietnam. It serves numerous internal and international destinations. It is used by a lot of companies so you can chose from flights with different prices.
Noi Bai is often the starting point for holidays in Vietnam as some flights arrive direct from London. As this is also your first stop in the country you need to prepare it.
It takes about 45 minutes to get to the centre of Hanoi and there are various ways of doing it. The most expensive is a trip organised by your hotel in Hanoi which often costs 300,000 dongs. You can also take a taxi and I recommend MAIL LINH or TAXI GROUP.
There's also the minibus for only 35,000 dongs; just before you leave the airport you can buy a ticket at the window and get on! You have to wait for the bus to fill up before it leaves!
The cheapest option is the local bus, it takes a bit longer but you get there eventually! It costs 6,000 dongs.
All three go to the centre of town so you won't have a problem finding an address.