He never will have a UKARA, UKARA is a retailers association.
UKARA run a scheme largely aimed at allowing them to continue in business selling RIF's to airsofters. They basically hold a database of players site registration details. This can be accessed by there members ( i.e. businesses ) to check if a player is registered at a site which subscribes to there scheme.
UKARA is not a licence neither is it your defence, your site registration is your defence, UKARA just provides one way to check it. You could simply provide your site details to a shop or UKBA if importing.
As for weapon recomendations I would recommend getting yourself down to a shop or site and try as meany different guns as you can get your hands on. If you decide you like the AR Platform I would also recommend the KWA/PTS RM4. It has all the reliability and ease of use of an AEG with some of the benefits of GBBR's i.e. recoil and stop on empty. If you can't run to the price I would say try either a G&G Combat Machine, which is a polymer entry level gun. Don't let the polymer construction put you off it is a very well built and reliable gun. A price point between the two I would recommend a G&P M4, they make about a million different versions, all solid well built guns.