Send the letter. All it will cost you is a stamp and may save you some time and aggro from debt collection. Don't send the letter and any creditor will carry on doing its debt collection routine. They can do that after the letter too of course but at least they then they will know what the situation is. Expect some including HMRC to chase the company for payment until it is dissolved no matter what you send. You cannot avoid agents or bailiffs turning up at the address, short of providing a new address for the company. Not that they can do much with a residential property or a place your business is not at.