Very impressed that you are thinking about this so carefully, most people I know just want a horse, buy one, and run into all kinds of difficulties!! You'd be surprised how little some people ask when selling on a horse.
I think the suggestions above are good - in particular starting with a part loan would be a great way of wading in gently rather than diving in to the deep end, plus obviously it is a lesser commitment in terms of time and money.
I would be careful selecting where any horse is kept (whether yours or on part loan) as I've seen this make or break horse ownership for some. For instance, I'm on a VERY small yard with few facilities - works fine for me, but we've had new owner/horse pairs move on in the past and really struggle as there really isn't anyone around to ask advice.
When I first had a horse, I was at the riding yard where I had been having lessons, which meant there were knowledgeable instructors to help out, safe places to ride without hacking out, and I could continue having lessons, either by myself or you could just pay a small amount to tag on to a group lesson on your own horse. There was also a great social side to the yard as it was a large, busy yard. They even did BHS courses once a year and held/ arranged transport to local shows.
The other thing I'd say is make sure you factor still paying for lessons into costs - I see so many people buy a horse and never have a lesson again. Having lessons on my own horse was so different from riding school horses; previously I was being taught how to ride; afterwards I was taught how to school my horse, if that makes sense? With a new horse, they will often test your boundaries and it is very easy to get into bad habits with them so I think lessons, at least to start off with, are a real confidence booster and help you establish your relationship with your horse.
I'd also go for a lovely schoolmaster type, something you can enjoy riding that will happily school, hack, pop over a pole if you want to, and that is good to handle from the ground, rather than anything flashy or too young.
Sorry for the essay, but hope it is helpful. Best of luck achieving your horsey dream! 