This seems fairly normal for UK broadband. I no longer live in the UK, but I travel for work a lot. At home (sweden) my broadband is pretty good, I don't experience any issues with it, even when twitch reflex gaming online.
When I travel I can usually manage to game on hotel wifi. As you can imagine this can be a hit or miss affair - but I've had fairly good results even then.
In the UK? Visiting relatives? Visiting relatives who use Bt Broadband? Oh dear lord. I've had better experiences in hotels! The amount of packet loss I see is shocking. Its as if some of Bt's nodes are basically bundles of string in a puddle and serving half the country. (and it wouldn't surprise me if they were) - it pretty much makes online games unplayable.
How you Brits still in the UK can put up with this is beyond me.