When you first start to explore the world of airsoft it can be quite daunting, with a copious amount of laws, brands, guns, gear etc. Hopefully I can break all of this down to make it easier for you to get into the sport.
The first thing you should consider is finding a site to play at. This can be achieved by using the incredibly handy online airsoft map: http://www.airsoftmap.net/skirmish/. With this you have the ability to seek out the best airsoft site for you, from here you can then start to think about equipment and guns.
Once you've been to your first game and decided that airsoft is for you, you should now start to look at getting your own kit. This is due to the fact that if you are going to get into the sport, renting guns at every game isn't cost effective.
The first thing to consider when getting into airsoft is the guns. Now, before finding one you like, you should learn about the UKARA laws. You have to be 18 and over in any case to buy an airsoft gun, but unless you hold a valid "defence", it is mandatory to get your gun sprayed 51% a florescent colour which will make it "two-tone". However, fear not, if you don't want a two-tone gun, you can look into "UKARA" (http://www.ukara.org.uk/). This means you have to play 3 games in no less than two months at a UKARA registered site. You can then go on to fill in the form on the UKARA website and you will be issued a UKARA number, which you can use to buy airsoft guns. (Note: If you are under 18 you cannot buy an airsoft gun. You can, however, get one gifted to you by someone over 18, meaning no money or services are exchanged in return for the gun, it is simply a gift.)
Once you understand the laws, it's time to start getting into the world of airsoft merchandise!