uk landlord

We recently moved into a privately rented flat, which looked lovely when viewing. After a month of living the boiler broke, it works some days and others it doesn't. My OH has a one year old son which we have over every weekend for 2-3 nights or more and have to take him over to my OH mum to stay if the heating won't work! The landlord won't repair it and has said that he will do it himself. Tonight when we went to bath little one the hot water won't work so we tried to re pressure and realised that the boiler is leaking and everything in the cupboard is destroyed!! We want out of here asap because we don't think it's safe for little man to be in the flat in case the boiler was to blow up or a gas leak. Is there anyway to break lease? We've got 7 months left in the contract