I have friends in the Bristol (UK) area and use this airport to travel to them.

As I do not drive, most of the time one of them comes to the airport to pick me up after the flight or drop me off on the way home.
They always seem to have to pay for the 'pleasure' to come to the airport.

Traveling by bus instead does not seem to be a cheaper option, as you have to pay a premium to use the airport stop on the bus lines.

Is there a way to travel to and from the airport without having to pay a parking fee or a much more expensive bus ticket?

I am mostly not able to walk any distance with my luggage but at times I travel with only a small backpack and I can walk about 3 km / 2 mile or so, as long as it is safe walking.