I think it depends on the courier that the company uses. Some leave it at the door, others at a post office. Sometimes, you can request a signature upon delivery - if you do that, then if no one is home to sign for it, they take it back to the warehouse and you have to pick it up. But warehouses/logistics centres aren't usually close to suburban areas because a lot of freight goes to and from them, which would create a lot of noise pollution. Not something that is particularly wanted in a residential area. It'd be a lot easier though if you have a car and can drive.
Before ordering, send a query to the company and have them outline their shipping procedure and the delivery method they use. From there, see how it'll impact the viability of having it delivered to your place under your circumstances.
I would recommend you Molicare Super plus first of all. They can last quite all right.
Secondly, if you want it to be delievered to the post office, then I presume that you want to collect it from the post office and not from a P.O Box. As Lukie says, he got it right. Some leave it at the door, but most of the couriers I know won't because if the cargo is lost, then they will be held liable. They would just put it back at the post office or warehouse so that you can collect it yourself.