A post that has come up quite often is how to change an old stoptap on a leaded supply.
You will need a fitting called a Lead Loc which is basically a compression adapter to go from lead to copper.
There are a few different sizes so ensure you get the right one. Details on sizing can be found HERE.
When you have got your fitting, turn off the water in the street and cut the lead main with a hacksaw. Clean it up with wire wool and fit the Lead Loc.
As lead is not a strong metal, do not overtighten when fitting.
Fit a small piece of copper pipe in the opposite end and then attach your new stoptap.
Make sure the arrow on the stoptap is pointing towards the flow of the water.
From there you can carry on in copper pipe to your other outlets.
If your incoming mains water supply pipe is lead, you should strongly consider upgrading it to 25 mm MDPE pipe as you WILL get more pressure AND you will no longer be drinking water that may have lead particles in it. :(
It is worth asking your Water Company if they have any schemes available to change lead mains at a reduced cost or even for free. :D