I have had a new MDPE water supply put in and now need to cap off the old lead pipe. I've dug up outside and found where my branch pipe comes off the main supply pipe, under my back yard. I need to cut this off and permanently seal it. I think I can use a Leadloc fitting to copper and then a short piece of 15mm copper to a stop end. BUT... I can't turn off the water supply a) because I don't know where it can be turned off and b) even if I did, it would presumably turn off the water to the whole row of houses. Is it possible/safe/wise to just cut the branch pipe and try to get the leadloc on quickly, or do you have any other suggestions.