I am boggling slightly at the idea of someone of BMI of 29 requiring a hoist!
I have a BMI in the low 30s and have had one homebirth with water, and am planning a second. In my first pregnancy my midwives were totally supportive and I just had to see a consultant (turned out to be registrar) as a box ticking exercise - they spent the whole appointment discussing my SPD and never mentioned my weight.
This time round I have diet-controlled GD and had to be signed off properly for a home birth by the consultant. Luckily he is very supportive of HB and was happy to do so. Again, my brilliant community midwives have been very supportive and were prepared to fight for me if necessary. If I'd been left to the normal midwives however it's clear that I'd have had a big battle on my hands.
I'm glad your hospital's policy has changed. I was going to advise you to see someone senior clutching a copy of the NICE guidance on homebirth, which IIRC state that BMI from 30-35 should be no barrier providing there are no other health concerns. MLUs are often stricter on the women they'll take than on what will be approved for homebirth, if you see what I mean, but it would be a good start. And you could always consider homebirth to make sure you get a pool-that was my main reason for doing it with my first.
I asked about this when I went into triage over the weekend (long story - all is well though!) and they told me certainly in Edinburgh the cut off is BMI of 35 and this is based on your booking in weight. She also said that, certainly in Edinburgh again, if you didn't qualify for it at booking they'd have told you there and then. Here they consider anything over BMI of 35 to fall into the high risk category so they try and steer you away from a water birth anyway apparently.