The local water boad has a duty to repair it free of charge.
We recently had a leak from an underground pipe and it was on our property, this means it was our pipe by law but the water board fixed it free. We had to phone them lots and it took 6 days for them to come out but they did and it cost us nothing.
We looked into taking out a policy and waiting 14 days but there was no point. Firstly check your local waterboard website - they have a duty to reduce water wastage and this means repairing the leak, even if they won't guarantee a repair date they will have to do it. Ring your household insurer and confirm that any damage to your property eg damp will be covered by the policy and even if you leave the water to run for weeks you should still be covered providing you have accidental damage.
Our leak was in the side entry to the house and Severn Trent dug it up and put everything back, good as new!
Good luck with sorting it, hope everyting is ok. x