I am planning an HBAC in the next couple of weeks. I have also doulaed for an hbac mum, lovely birth, despite a lot of pressure from the consultant (even on the day) for her to be in hospital.
They will say no, because that is the policy, but the choice is yours.
I had a horrendous time in hospital, and it was going to hospital which stalled my labour and ultimately led to me having a emcs I might not have needed, it was classic failure to wait. I have a slightly high BMI, but apart from that it is just the VBAC that makes me "high risk". Ultimately me and the consultant both wanted the same thing, a successful natural birth, but we disagreed on the best way to achieve it, she thought that being on a continuous monitor would be safest, I felt I would labour better (and quicker) in a home environment, and feel safer with 2 midwives monitoring me (rather than a machine) regularly.
Get a copy of "Vaginal Birth After Caesarean, the VBAC handbook". vbacfacts.com is also very good.
The 1 in 300 figure is also falsely high when you look at the studies that produced the figures, about half of those are dehiscience, where the scar splits, but not right through, this usually isn't diagnosed until afterwards. It also includes ruptures before labour starts, induced labours (much riskier in terms of rupture) vertical scars, close spaced pregnancies (less than 2 years), so it is not really an accurate figure in terms of your risk of catastrophic rupture. Of course there is still a risk, but it is less than is usually quoted.
The key with HBAC is to have your midwifery team on side. You will likely meet with your HOM or SOM to organise a plan. On their side they will make sure a confident, experienced midwife is rotaed in on call for you when you are due. They will suggest a schedule for monitoring, and the markers they will use to transfer in (for instance they won't want your second stage to go on for more than an hour, so if pushing is slow, they will suggest transfer, you can ask them not to direct you to push though, and see if your body does it on its own) you don't have to transfer at any point if you don't want to, but they will want to go through what they think is best in advance with you.
Be prepared for a lot of "informed consent". You will be repeatedly told the risks of the choices you are making (including when they arrive and find you in established labour), and the worst case outcomes, this is just so they know you understand, and ultimately they are likely to support you in your decision, unless there are lots of other risk factors working against you, in which case they will give you strongly worded "advice" against it.