Wapsmahoney Congratulations!!!!
Lovely news!
Exciting potatos! Annoying to miss out on a nights sleep, you'll have to try to take it easy if you can, encourage things to get going!
Hope stuff gets moving soon for you Cineraria!
Pingu I had a water birth with DS! It was fab, so hoping for the same again. How many pools are there at your hospital? I did a bit of research at our hospital before hand, and they only have three pools, but less than one baby a day born in the pools, which surprised me as the idea of water birth seemed very popular with my peers. Turns out a lot of the time they're out of action because a) someone who doesn't actually want a water birth is using the room, or b) it's been used and not cleaned yet!
The key is to let the mat unit know asap when you're in labour, even if you're not ready to go in yet, and let them know you want a water birth. That way they know you're coming in, probably in the next 12hrs or so, and can try to make sure there's a clean one available. Just keep reminding everyone that it's what you want every time you speak to them, when you arrive, when you get on to the ward etc!
The other issue with water birth is that you'll need to get to 5cm dilated before they like you to get in to the pool, as it can slow labour down if you get in too soon. Getting there with just gas and air can be a challenge, esp if you're back to back or there's any other issues, and if you've had anything stronger it does rule it out, so bear that in mind. I managed with hypnobirthing so hopefully you'll find it works for you again - I hope you get one!! 
Lol, sorry, that was a right essay 
Im also on constant labour watch - it really does feel imminent, but it could be three weeks yet!!