Hi McBaby - I also have hypermobility syndrome, and it does ramp things up a bit. I've been signed off since about 18 weeks for the PGP and in my first pregnancy I was on crutches/120mg codeine a day. I'm 33weeks now (2nd time round) take no more than 30mg codeine a day and can walk just fine... so I know it doesn't have to get worse just because of the hypermobility. I also have a 2stone toddler to care for which means I'm not exactly a lady of leisure! I have handled it much more pro-actively this time which really, really helped.
My top tips from experience are to move as much as possible, truly, don't sit, stand, walk or do any one thing for more than 15-45 mins depending on your pain level. I actually have a timer stop watch for tasks like washing up. I set it for 15 minutes and when it dings, even if I'm not done, I stop, move around, sit down, then go back. Keeps things from siezing up and stops me from bending over or doing awkward jobs for too long, then regretting it!
However tempting it is to lie down or watch TV for ages don't do it without getting up and moving around every ad break! Seriously, every, single, one. Also, get satin pj's for bed so you can slide around if you turn while sleeping as this takes the least effort to move/turn over. Get a dreamgenie or similar pillow so you have support below your bump but especially between your knees when asleep - keeping your knees two-three inches apart and parallel will ease the symphysis pubis pain a LOT.
Take your pain control by the clock no matter how you feel. If you have a good week, you can try to reduce the dose (I've dropped from the higher dose of 15/500 co-codamol every 6 hours when I was 25 weeks to 8/500 now) because painkillers work by building up in your system not by reacting to your actual symptoms. If you have a pain free afternoon great! Top up anyway, to keep that going. Like me you may find that you can decrease the top-ups as time goes on rather than escalating the meds (which is what I did first time round, when I took them more erratically). If you manage this you will avoid some of the withdrawal problems for your baby at birth that opiates can cause.
See your physiotherapy team and ask for a pain clinic referral - they can put you in touch with alternative therapies on the NHS, at my hospital they offered acupuncture(which is great) and reflexology. Take any and all help offered! Contact your local Red Cross medical equipment store - google it - and borrow (for free) perching stools for the kitchen, walking frames or crutches if you need them, even wheelchairs. Use mobility aids before you feel like you can't manage without them! They work on so many levels, obviously they help you when you really can't move well. But they also slow you down, remind you to take things easy and are a visual cue to other people that you are ill as well as pregnant. It's amazingly helpful to have people at the supermarket offer to push your trolley (don't push anything you don't have to - hoover, trolley, buggy etc, it's terrible for pelvic instability). Also gets people to open doors etc.
If you use a support belt, try upgrading to a Serola one (you can get them on Amazon) but only use it when you are needing the help, don't wear it sitting down or all day as it will weaken your muscles longer term.
The birth is another story. I suggest you look on this website and pay attention to the birth plan bit. Then book a consultant or senior midwife appointment well before the birth (36 weeks is a good bet) to discuss your options and go through your birth plan. First time round I was offered this appointment at 39 weeks, baby arrived 38 weeks and no-one was prepared for the problems I had moving - I ended up with a forceps delivery which was less than ideal. Hence I have a section booked this time, well in advance! But a section isn't necessary or even ideal just because of PGP, I have other complications left over from last time which make it the best option for me. So definitely push your midwife to get you this support early. You just don't know when baby will come and it's best to be prepared.
If I can think of anything else I'll post back again! Good luck :)