Is it permissible to buy a house in Britain that requires paying annual fees to an insurance company, which include usurious interest, given that this condition cannot be avoided, and this is done to avoid usurious borrowing to buy the house?

There is no objection to paying money to a company that manages jointly owned property, as this falls under the category of ijara (leasing). The sin of the company depositing money with interest (usury) rests solely upon them. If the insurance is obligatory for you, then there is no objection to it, because necessity removes hardship. Sheikh Ibn Uthaymeen was asked about a Visa card that includes an usurious condition if the client delays payment, but livelihood necessitates it. He replied that there is no harm in it if the hardship is certain and the probability of delaying payment is weak, because the necessity is real and the delay is doubtful.