For sure take lessons for a while. it depends on your ability,and your trainer etc when it comes to how long you need to ride before you lease a horse-it also depends on what you want to do with it. ie jumping,pole bending etc. I had been riding for three years before I leased my first horse. You need to know how to everything yourself,including tacking up,grooming,and riding and controlling the horse.
I suggest leasing the near you. When you lease you want to be able to see the horse as often as possible. There is no point if you would have to travel a long way. It depends on how far away the "country" is. I bet you could find riding stables near you,just google it-or look in your yellow pages etc...there could be adds.
No riding boot are really cheap. But thats an opinion I suppose. Seeing as you probably dont have adult sized or so feet I suggest paddock boots(English...western may differ.). They are less expensive and would fit you better more likely. You will have to find a tack store around your area. You could try and animal feed store\outdoor store or something of that nature. Breeches the same thing..or you can look online...I get my boots from Dover.com. They have good brands. If you dont want very good boots,or are just looking for something cheap,try antique or thrift stores. Really do. Sometimes you find decent boots for very cheap.
I suggest you get good experience with horses first though. Learn how to ride well,and control the animal. Learn how to take care of it. Don't forget that when you lease many people will NOT let you keep their horse anywhere. Generally the full owner decides where to keep the horse. You usually have to pay half of everything as well. Half the vet and farrier bills,half of the stabling...and the expense of lessons,boots,clothes,a helmet,and saddle.