The birth pool in a box is big enough for both of you.
I mentioned it to the MW at my booking in appt (10 weeks), she just jotted "would like home birth" in my notes. She just suggested I have a birth plan done for my 34 wk appointment so we could go through it (I ended up going through it with a different community midwife as my named one wasn't there for my 34 wk appt). Then my 36 week appt involved a visit at home, my MW brought a birthing kit, took bloods and wrote a management plan in my notes (i.e. when to call them etc).
I think they don't discuss it seriously til around 34-36 weeks in case you develop complications or change your mind in the meantime, on the other hand it gives you plenty of time to research!
I had to be seen by a cardiologist between 30-34 weeks, but I made sure he wrote "suitable for home confinement if she wishes" in my notes