IIRC theyoungvisitor has it pretty well right - you can insist you're staying at home and, once they know, the MWs has a duty of care to look after a woman in labour. But that care doesn't have to be provided in the form of a MW (although it usually is).
I'd definitely 2nd the IM option if she can afford it (and its always worth talking to them as they can be very flexible with payment plans and bartering) - DD was born as a breech baby at home with IMs and it made such a difference feeling totally confident in what the MWs were doing. It is important to talk to a few and make sure you're on the same wave length, though - no one gets on with everyone, afterall!
Its also worth remembering that your friend doesn't have to see the consultant if she doesn't want to - it may be policy within her PCT for her to be under consultant led care after the complications she experienced last time, but as she's not their employee she's not bound to abide by it.
If she wants to stay within the NHS then I'd recommend discussing what her HCP's are concerned about, what the risks of that happening are and how it would be handled differently at home vs in hospital. Once she understands all of those she's in a much stronger position to write to the head of midwifery stating that she's aware of these issues and, assuming no further risk factors arise, she is making an educated decision to birth at home and expects to be supported in that choice. Or she may choose to go to hospital aferall - but if she doesn't understand why they're saying she "can't" have a HB its difficult to argue her case (and IMs may well give her a generic response on an initial inquiry, so another useful source of info).
In addition to the website linked to by TYV, both the homebirthUK mailgroup and AIMS are usually very informative and supportive, with a lot of experience in dealing with obstructive protocol.
Hope your friend has an easy pregnancy and a more straighforward birth this time round