Jen - wow thats AWESOME news!!!!!!!!!!!!!!!!!!!!!
So sorry I didn't post earlier - I did look on the other side a while ago - but for some reason didn't see anything. Anyway here i am posting at some ridiculously early time in the morning instead suffering for mad pregnancy insomnia (all this awaits you!!)
I had the same dilemma and we decided to bite the bullet and go privately in the end - mainly becuase I wanted the same person the whole way through and i couldn't see anyway of guaranteeing that without paying for it. I really do think that the NHS would have given me as good as care as I've had privately but I must say I don't regret paying up (so far!). I geta scan when I want , get to see a doctor when I want etc etc -all of which was pretty important to me - but its very personal
We traumatised over where to go (and don't worry you have MUCH more time that everyone say you do to decide !)
For us it came down to The Portland, St Thomas or St MAry - both of which have privtae wings. The latter 2 have the advantage of being attached to NHS hospitals in case anything goes wrong. Bear in mind that if you go 100% private you will have to pay for neonatal care if needed - when you are suddenly talking mega bucks.
Without that it'll probably cost around £4000-£5000. Still not cheap.
A cheaper alternative is to go for amternity led care at the Portland (as per Portland babies on the TV) - this way you still get one on one care - and its all quite nice I think!

. You get a doctor if anything goes wrong. Ignore all the scare stories you read about the Portland - its a good place. The only downside for us is that our insurance wont cover ANYTHING and we were worried about the cost if we required neonatal care.
Anyway - about £4000-£5000 is the answer. Pretty scarey!
But Phil is right you have to go for watford look at other options too.
Good luck -keep in touch!
Cazxx