I agree with Sian. You don't have to have a puppy, there are loads of rescue dogs of all ages, shapes and sizes, temperaments and capabilities just waiting for a home. Often they're already house-trained, and will sit and get in a basket on command. Some dogs in shelters just got lost, others do have problems. Some are outright psychopaths - don't start with one of those.
Watch a few wolf programs to get the hang of dog behaviour.

Most shelters will be only too glad of an extra volunteer dog walker while you try out if a dog is your thing / decide what size and shape suits you. You'd also get first choice of the new arrivals.

It only takes a couple of weeks to bond a dog to you - some dogs it's a couple of minutes.
The Bearded collie we've just lost to kidney disease was the best anti-depressant I've ever had.

Be prepared to upgrade your vacuum cleaner if you decide you like shaggy dogs - and edit your visitor list to exclude those who customarily go about in expensive posh clothes.

Our two think the best thing in the world is jumping on us early in the morning and turning upside down, then snoring loudly for an hour.
Before licking us enthusiastically.
Apart from running like......for miles along the beach of course.

Good luck
Paws