How often can I fly my own small plane?
Depending on what country you live in, yes, but it will cost you.

It's probably the cheapest to fly an airplane you own in the United States.  Here, the answer is yes, with very little restriction, you can just drive out to the airport and fly an aircraft within the National Airspace System.  You just must abide by the legal and medical requirements for you, and the legal and operational limitations of the aircraft.  Most airports throughout the country are uncontrolled, so you may have limited, if any, interactions with ATC.  The ability to fly pretty much anywhere you like with very few restrictions is what makes GA so appealing in the United States.