Erm yes, and no.
There are a few minor exceptions in UKARA, but you must jump through a hell of a lot of hoops, and must have proof that what you are doing does indeed require the use of RiFs.
Films/Plays. But, you must have proof that you are actually doing this (i.e production company details). That said, most films that do use airsoft RiFs, tend to rent the gun, so it isn't permenant.
If you are a reinactor, then you could be exempt, providing you have the group membership details. I'm not entirely sure though, as most reinactor groups I've seen tend to use de-activated real firearms, or simple replicas.
Deactivated SA80s, specifically L85s - you could be looking at anything from a few hundred, to a few thousand quid (yes, I have looked :lol: )