I couldn't not reply to this, having just gone through it 3 months ago!
I ended up with a c-sect with DS1 after he failed to descend after 3 hours of pushing (he was posterior, 11 days over). I went through the midwife clinic when I got pregnant with DD and they were more than happy to allow me to attempt a VBAC but was told I wouldn't be 'allowed' to go over 41 weeks without being either induced or ECS. Fast forward to 41 weeks and still not in labour, I was booked in to have a catheter induction. When I rang the hospital to go in the OB on that night refused to do it as in his experience induced VBACs always
failed and it is much better to go into natural labour. I agreed, but got very upset with him so he agreed to see me in clinic the next day. He ended up convincing me to book a CS at 42 weeks (5 days later, next available time slot) but gave me a S&S just in case and found I was already 3cm dilated. I went into labour that afternoon, convinced I would end up having a CS anyway (the ultrasound that morning showed DD was posterior) but thanks to my awesome midwife she was born naturally 6 hours later!
As far as the risks of going overdue go, I'm not sure (and feel free to correct me), but they are the same as normal pregnancy (placenta breakdown etc), however you can't be induced with the prostaglandin gel or syntocin because of the risk of uterine rupture along the CS scar. So if you go overdue they don't like to induce you and prefer to just do a CS.
I'm so, so glad I had the opportunity to VBAC and I'm lucky that I had no medical reason to need a CS earlier. I debated my decision so much until DH pointed out 'If DS had been birthed naturally it wouldn't even be a question of whether or not to have another natural birth or ECS' (meaning, that if the midwives were happy to treat me no differently to any other pregnancy then why even contemplate an ECS). It was such a relief to just start going with the flow! Sorry it's long but hope it helps