What pipes to insulate under floorboards

[Michaelsf90]

I'm replacing my kitchen floor and altering some wiring so while I'm under the floor I was considering insulating the heating pipes to reduce heat loss. Only using the cheap grey foam that's about 99p for a metre. Also offers frost protection. Then it dawned on me about the cold water main coming in. Should I insulate that as well to prevent any damage from frost and cold temperatures? It may seem a daft question but the incoming water main is lead. Would this pose any kind of problem or risk if I insulated it? The pipe may go under ground inside the house which if it does I obviously can't insulate it. Thanks for any advice

 

[JP_]

I'd insulated everything, and consider replacing the lead pipe too.

 

[Michaelsf90]

Yer the lead pipe needs replacing but I don't fancy spending thousands when we may move in the next 3 to 5 years. If the pipe goes straight from the outside stop tap then previous house owners built a small extension on the side of the house where the cold water main runs. That's if it goes straight from the stop tap and then bends into the house further down

 

[Michaelsf90]

Also can I use expanding foam around a lead pipe? It won't affect it any way will it?