If you're expecting your first baby then it's a really good idea to attend antenatal classes - not simply because you will learn so much about the birth process, but also because you will meet other local mum's and couple's all going through the same experience as you. Antenatal classes are offered nationally by the NHS and the NCT.
NHS antenatal classes are offered for free in most areas and are open to both expectant parents although it's more usual just for mum's to attend. Classes are held by midwives and cover the birth procedures within a hospital environment. You will usually be able to attend a tour of the maternity unit where you are planning your delivery which is highly advisable so that you can familiarise yourself with the surroundings.
NCT classes are held by trained adult educators either in their own home or at a local venue. It's common for partners to attend these informal classes which run for several weeks prior to your expected delivery date. The NCT offers a variety of classes in addition to antenatal ones but your first contact will probably be for antenatal classes. You must pay to attend NCT classes but there are significant discounts (90%) for under 18's, students and those on support. The cost of NCT classes also includes optional NCT membership which you can choose to opt out of.
You don't have to choose between NHS or NCT classes - you can attend both.
As well as learning about the birth process and getting the inside track on your local maternity unit, antenatal classes give you the opportunity to meet other expectant mother's who live locally to you. It's common for these mum's to become close friends in the months following birth as you'll seek advice from each other, and start seeing each other in local playgroups, at the doctor's and you'll keep bumping into them in town. Use the opportunity to develop a local support network of other new mum's, it's an opportunity that you won't regret.