Sorry to hear this, Chairboy.
Fire is always one of my major concerns. I double lock my front door at night but, most importantly, the secondary lock is operated by a splined key which is always left in the door. (It's not possible to access that key from outside) If I have house guests, which is often, I instruct them that to open the front door, the bottom lock must be released by turning that splined key. At the rear of the house, my conservatory has those windows which tilt open or can swing open (German design I believe). So I think I'm OK.
During the last election campaign, I was making a lot of house to house calls, sometimes at around 10-11am on a Sunday, before most people had come out of the house for the first time. And I was amazed at how many people came to the door, tried to open it, and then realised it was locked from the inside and had to go hunting for the keys. My advice is always to leave that key in the door for a fast exit. Same thing goes for hotel rooms, if it's the type of lock that is locked using the key from the inside - always leave it in the door before you go to sleep. If there's a fire, the power might go out - no light to help you find the key, except the light of the fire, by which time it will be too late.