If you have insurance call them as they can look at an emergency plumber over the bank holiday, but you will normally have an excess to pay so just check that too. Hope you get it sorted.
I had this rhe main pipe from outside burst under my livingroom floor I had to have my floor dug up so they could find it my living room and hall was under 2 inches of water.
The external mains water pipe would run under the house, if you have a leak on your property it’s down to you to sort it, the water board doesn’t do it anymore 🤯 what is your water pressure like?