NATS have traditionally used Racal Jetlites and, before those, Astrolites, as have several non-NATS units. Not sure what they go for these days. I think it depends on the unit. I believe at Edinburgh they use the Airlite 100. Some airfields may still use the Airlite 62. At Leeds Bradford they use an obscure Plantronics device. I say obscure because I can't find any info about it but having worn one it is binaural, very light, lousy audio quality and flimsy as hell. Not good.
If it were my choice, I'd go for the Sennheiser HME or HMD 46.