Has anyone replaced a lead water pipe from mains to their house? Should I bother?

Hi

When we bought our house around 9 years ago, our survey showed up that we had a lead water pipe from the stopcock to the mains.   This was described as a "medium" concern that we should consider having replaced with non-lead piping.  Needless to say, I've done nothing about it.

We're just about to have our front garden re-tiled, and I'm wondering if I'm being a bit hasty with that work if I should really be having the lead water pipe dug up and replaced first.

We've got 3x small kids and I am (I think) being slightly paranoid that the pipe may cause lead in the drinking water which could be harmful for them.   I bought a water testing kit, which didn't seem to show any lead in the water - although I'm not sure how reliable it is. 

Has anyone else had similar issues or replaced a lead pipe coming into their house?  Even if not, any views on how risky a lead water pipe is would be appreciated.

Thanks

Ian