There is a world of difference between purchasing a puppy from the 3 common scenarios - a puppy farm (breeding purely for profit, usually in large quantities and not in the home), a backyard breeder (the type who take their female to the nearest male of the same breed to pay for a nice family holiday, but do not health test or prove their dogs in any manner) or a reputable breeder (who will health test their dogs for any genetic diseases that could possibly arise in the breed, and base pairings on improving the breed in terms of structure and temperament).
Obviously the only two responsible choices are to get your dog via a reputable breeder or a reputable rescue. Unfortunately there are plenty retail rescues who buy from puppy farms or import from other countries with the intentions of selling on to the first person who comes along with cash as an adoption fee.
Both reputable breeders and reputable rescues will send dogs out on contracts that the dogs are to be returned to them at any point in their lives.
Both reputable breeders and reputable rescues will temperament test and place dogs accordingly in homes best suited to their needs. Personally I like to see a breeder who uses a temperament testing system such as Volhard Aptitude Tests, similar logic based testing is rarely seen in rescues unfortunately. No reputable breeder or reputable rescue will let you choose your puppy or dog based only on appearance or 'this one approached me first', with no regard to temperament and suitability. It's a massive red flag if a breeder lets you choose your puppy or offers 'first pick', sadly it's still very common in rescue but thankfully some rescues are catching on to the use of appropriate temperament matches to increase long term suitability of placements.
Depending on the breed you choose, expect to wait for up to 2 years on the waiting list of a reputable breeder. For rescues, waiting times will completely vary based on breed or type preference.
I'm heavily involved in both rescue and the world of dog showing and sports. Both have their strong points. Personally I'd happily never have a dog below the age of a year again, puppy raising is extremely demanding in terms of time and energy.
Don't let your garden situation put you off applying to reputable rescues, especially breed specific ones are more likely to consider your family based on the merits of the fun filled life you can offer to the dog, rather than the size or set up of your garden.
Regardless of whichever option you choose, please do it responsibly. Do not fall for a cute picture on a sales site or social media. Get to know your breeder or your rescue, and expect them to ask you lots of questions in return.