I'm 20w pregnant with #1, living in Greenwich and assigned to a team of MWs based at QEH.
I discussed birthplans briefly with the first MW at my 10w appt; she was very in favour of homebirths, and is planning one herself (2 weeks ahead of me, so she won't be attending mine!).
At my 16w appt, I said I wanted a homebirth; the MW said I didn't need to decide yet, but that she'd make a note of it now and we would discuss the details at the home appt later in pregnancy. I got the impression that she was fully supportive and it wouldn't be an issue in theory (she asked a couple of questions about where we lived and what kind of accommodation, but nothing other than that).
I had an ob appt at QEH the week before last, as I have a heart condition, and she was also fully supportive of the plan for a home birth - in fact, said it would probably be better, in light of the heart condition.
So - I don't know what happens in practice, but certainly so far I haven't been made to feel that it will be an issue at all. I also got the impression that the midwives rather like planned homebirths, as they're less hectic than the overcrowded hospital! I had raised a couple of potential objections, which were quickly overruled - e.g. terraced house (response: you won't give a monkey's about the neighbours hearing when you're giving birth), possible mess (response: we throw a plastic sheet over everything, tape it halfway up the walls if you're worried, roll it all up at the end, no problem); issues with transferring (response: we'd call an ambulance at the first sign that anything was wrong, it would be with us within 10 mins, you'd be in the operating theatre within 20. We're trained to spot problems before you have them). I really didn't get the 'hmmm... well, it's your choice, but...' that I had been expecting.
So far I've had a crap experience of the hospital itself (failed D&C in Oct (retained products, necessitating a private D&C), 6 hours in A&E at 14w with this pregnancy, filthy loos in both areas) and I'm reluctant to go back. The MWs seem to fully understand my reluctance - the last one even wrote about the A&E experience in my notes, with the extra note: 'care received was substandard. Apologised!' I've not seen the antenatal or L&D rooms so can't talk about those.