I've been called twice - once years ago, when I had a toddler, a breast-fed young baby, and a Dh working abroad. I was excused.
2nd time was a couple of years ago - 2 cases, just the standard 2 weeks. I found it very interesting, and reassuring to see how it all worked in real life. In particular I was reassured by both judges impressing on us that if we had the slightest doubt of someone's guilt, we MUST return a not guilty verdict.
Another thing I've never seen on TV - when we were taken off to deliberate, the usher also had to swear an oath that she would not allow anyone to speak to us or contact us in any way about the case.
Also found interesting posters on the jury room walls, with really severe warnings about discussing the case outside, or using google/internet to research the defendant. A former juror, a senior academic who you'd think might know better, had been banged up for several months for doing precisely that.