I have no idea about the brands in the UK, but I can tell you that I had severe dry eyes after my lasik, and just used generic artificial tears and they worked great. I would imagine if you go into any Boots pharmacy there in London, they probably have a ton of different options....
I lived in England for a year and a half, and I always had good luck talking to the pharmacists there (in Boots pharmacies) about any health issues I had, so you might try asking one of them! Good luck!