My DC3 arrived very quickly (about 40 mins) at home..my DH delivered him! I had an inkling that labour would be fast as my previous births had been quick (2-3hours) but I had been told by a midwife that it was unlikely to be really quick as I had a 5 year age gap between DC2 and DC3
I had planned for a home birth anyway. Woke up at 5am with fairly strong contractions. Called the midwife around 5.15am. It soon became clear that labour was progressing very fast so my DH dialled 999, put the telephone on speakerphone, and was talked through what to do by a nice, calm man on the other end of the line. I remember he kept saying to make me lie down, presumably as it's easier to catch the baby (?!), but I was in grumpy, full-blown labour by then and kept refusing because I knew from my previous labours that it hurt more.
So, kneeling up against the sofa, I gave birth to DS at 5.40am and DH, thankfully, caught him. The midwife and the ambulance crew were actually knocking at the front door by then and my DH was shouting at them 'I can't unlock the door, I can see the baby's head!' As soon as DS was out he handed him to me and I can honestly say I have never seen him move so fast as he did then to get to the front door and let the professionals in.
Which brings me to tip number 1:
If you end up calling for an ambulance DON'T FORGET TO LEAVE THE DOOR UNLOCKED!
Also get your DP or birth partner to read up on the very basics of what to do. I think my pregnancy book said something like check the cord is not round the baby's neck, wrap the baby in something warm and don't cut the cord.
My DH also regrets not thanking the man on the emergency services line. In all the kerfuffle of the midwife and ambulance crews arriving the phone got hung up!
TBH I think my DH found the experience more scary than I did, I was too busy giving birth to have any spare head space to worry that the midwife wasn't there. Luckily it was a straightforward birth and my DH had been present at the births of our previous DCs. He says if he had not witnessed a birth before he would have been terrified!
It was actually a lovely, bonding experience, in fact a terrific high, to feel that we had brought our DS into the world ourselves. It was a few hours later that I suddenly had a panic attack about what I would have done if I had been on my own, or just with my older DCs, and my DH had been at work. The midwife calmed me down by saying that women tend to go into labour when they subconsciously feel safe, which is usually when they have their family around them. This is apparently why most women begin labour at nighttime, and why it is very unusual for a woman to give birth alone. I don't know if this is a fact, or whether she was just saying it to make me feel better but it sounds reasonable.
Anyway, good luck! Wishing you a safe and speedy delivery!