Home Births really aren't messy - I've attended some and had my own.
They'll deliver a box with all the info and extras that they'll need around 38 weeks (if i recall correctly) it'll have a list of any extras you may need or suggestion. Best advice is have some food and drinks ready for the midwives! haha.
We had a plastic sheet on the floor (rented property!), and some puppy pad type things, which caught my waters when they went a min or so before delivery. The only messy part I suppose is towels, they get a bit mucky but just from wrapping up baby and after birth etc. Nothing that can't be chucked in the wash straight away. Midwives are very good at giving it a tidy whilst you're basking in the after glow!!!
Only pain relief the midwives can give you is gas and air, in my area they carry two tanks each and I had two attend, so four tanks but used barely one. So, you do have a decent amount of time with gas & air, if needed. It was 20mins a tank but may have changed. Some areas the Midwives only carry one tank.
They don't stay too long after birth, long enough to tidy, fill out the paper work and help establish a breast feed. I'd say an hour or so, or longer if you need the support (depending on the time because you'll have another visit the next day). you really won't notice how long they're there, usually very quiet.
Honestly it's just wonderful to have your baby, clean up, get in to your own bed, not be disturbed, have your home comforts around, y'know? So intimate and unintrusive.