And then the bill came out with an additional 10% - 15% (can't remember exactly) added on to the bill as a service charge.
Some places try this on, its very rare though. I went to an italian place that did it once. They aren't allowed to enforce this tho, if the service was bad you can just tell them to calculate it without the service charge or just pay for it minus the service charge and leave. The reason everyone you were with just paid it is because we don't like to argue or cause any kind of fuss here. Even if we are being ripped of we will go along with it and then moan a lot to our friends/family afterwards about it.
I have chatted to quite a few English people after this and I was told that Brits tip just as much as the Americans. And tipping is expected for hairdressers and other things besides wait staff. So I am seriously confused!!
Not sure who told you this but I would challenge this, it seriously isn't the norm at all. I have never heard of anyone tipping a hairdresser!
How difficult is it to add (discretionary) service onto the cost of a meal in your head, before you order or before you pay??
Fair enough. If I ever went to the states I would do this. Still seems weird to me (and most of the non USA world) though!