Just put up the first set of links.

This one will take you directly to the UKARA registration site. Its primarily for retailers but you must be UKARA registered to purchase RiF's (Realistic Imitation Firearms). To do this you must be at least 18 years old and be registered with a UKARA Registered Airsoft Site for no less than two months and have played at least three games at said site. Once this requirement is filled you simply fill in a UKARA form and have the site stamp a verification on it. Then you just take it to your local Airsoft Retailer, with a form of ID (Passport, Drivers License or Bank Statement), and they'll add you to their database. At this point you'll be able to purchase your very own RiF.
Should you want to purchase online you'll have to mail your UKARA form off to the websites mailing address along with photocopied ID. This will take a week or so before you are entered into their database.
BE WARNED! You are not entered permanently and will need to renew every 12 months. Additionally you can be removed should you stop going to your registered Airsoft Game Sites or should you show misconduct.
Now you can purchase iF's (Imitation Firearms) without a UKARA registration but you must still be 18 or over. And as well as that the gun must be sprayed with paint to the degree of 51% of its body. Removing this paint after purchasing is also very very illegal and should you be caught with the gun WITHOUT a UKARA registration then you a liable for an ass whooping from the Police.
Personally I will be waiting for my UKARA registration before I make my first purchase. It'll give me more chance to choose which rifle I want as my first.

This second site is primarily for players to protect the sport and engage in conversation with the government because lets face it we are using replica guns which can be and have been easily construed as actual guns. It is essentially Airsoft's public face and shows how organised and safe Airsoft is.
UKAPU is entirely non-profit but is essential for the protection of Airsoft Skirmishing so I would recommend any new players to join. It only costs £5 annually but will give benefits such as discounts at Airsoft Retailers and at Skirmishing site. Additionally, though they can not offer any guarantees, should you be caught in a tight spot with the police or a border agency who are misinterpreting the law they can step in and aid you. Stick to the rules and they can keep you safe and legal.
Should you want to purchase online you'll have to mail your UKARA form off to the websites mailing address along with photocopied ID. This will take a week or so before you are entered into their database.
BE WARNED! You are not entered permanently and will need to renew every 12 months. Additionally you can be removed should you stop going to your registered Airsoft Game Sites or should you show misconduct.
Now you can purchase iF's (Imitation Firearms) without a UKARA registration but you must still be 18 or over. And as well as that the gun must be sprayed with paint to the degree of 51% of its body. Removing this paint after purchasing is also very very illegal and should you be caught with the gun WITHOUT a UKARA registration then you a liable for an ass whooping from the Police.
Personally I will be waiting for my UKARA registration before I make my first purchase. It'll give me more chance to choose which rifle I want as my first.
UKAPU is entirely non-profit but is essential for the protection of Airsoft Skirmishing so I would recommend any new players to join. It only costs £5 annually but will give benefits such as discounts at Airsoft Retailers and at Skirmishing site. Additionally, though they can not offer any guarantees, should you be caught in a tight spot with the police or a border agency who are misinterpreting the law they can step in and aid you. Stick to the rules and they can keep you safe and legal.