If you they are threatening a warrant of entry then it is presumably for non payment of bills?
regardless of how short a period you are living in this property by using the supply you automatically enter into a deemed contract with the supplier and therefore should be paying for your usage. If you have not registered with them and arranged to do so then they are more than entitled to gain a warrant of entry. Using the supply and not making arrangements to pay for it is theft. it is no different than walking into asda filling your trolley and walking out without paying!