You don't need to decide until 36/37 weeks because it doesn't affect the care you'll receive. The NHS midwives tend to do a home visit at that time to do a risk assessment and establish any access issues so they're prepared. They'll usually drop a birth pack at your house at this time too - just a box with gloves, incontinence pads, bin bags, a bucket etc so that whoever is on call the day you go into labour only has to rock up at your house without having to carry loads of crap in her car. The on call midwives exchange the emergency resuscitation and emergency drugs each time they hand over to one another each day - they bring that with them.
There's a really good homebirth for fathers book but as I'm on mobile web, I can't look easily for the name/author you (sorry). A good website is
www.homebirth.org.UK - there's a section for fathers there
Good luck!