I woke up early today and heard strange sounds. When they didn't stop, I got up to find out what it was. It was the boiler. I switched it off. So I had to work from home again today while waiting for someone to come and look at the boiler. It was freezing all morning!
A very nice and efficient guy turned up exactly when he'd said he would at 1pm. Of course it didn't make the strange noise when he switched it back on. He did a full service, reassured me that it's not going to blow up and I'm happy to have heating and hot water back again. And even happier that I don't need to get an expensive new boiler!