"can you listen to airband frequencies online? My guess would be no."
The aforementioned
www.liveatc.net is the main one and has a live feed for Dublin ATC but UK airports are strictly banned. Even when someone did post a feed for Durham airport on that site, the regulator OFCOM were on to the website in a flash demanding that it be removed. Being an American website they didn't have to obey but did so anyway out of respect for British laws.The Wireless Telegraphy Act bans listening anywhere but if you're minding your own business in a British airport they turn a blind eye. Not so with websites however.
PS Gate 22 , Aldergrove Radar is now 128.50