You probably need to work out what really appeals to you about an IM/worries you about NHS hb, etc.
I'm sure you've researched it, so you won't need me waffling on about how you're far more likely to cope without drugs at home, etc You may be even more likely to cope well if you have a mw you know and trust, however.
There is no reason at all to think you would be better off in hospital unless there is a valid reason why you or the baby might need on-the-spot medical care that can only be provided in a hospital. If you and the baby are healthy, home is the place to be, really.
It is expensive but you are getting a unique, personalised service from a fully-qualified professional and expert in normal childbirth - usually well worth it.
I'm completely pro-NHS hb but there are more variables. Is it just being at home that matters or the relationship you would build with your mw? Unless you're with a group practice on the NHS you might not know who will turn up on the day, as it were, and that can make a difference. If your Trust is supportive you're likely to have a perfectly good experience (for free!) but you might decide you want the security of knowing the mw long beforehand.
FWIW, I think it's very wise not to prescribe pethidine for a hb. Meptid has, I believe, fewer side effects for the baby (must look it up!) - much better for a hb. You may not even need the g&a anyway!
Sorry, bit rambly. Only you can decide but if you can afford an IM, and you really feel you have gelled - why not?