If you're having trouble getting on your bicycle, I wouldn't go for the clipless pedals just yet.
Work on getting that saddle height up to what it should be, and you'll likely find riding quite a bit easier. BUT do mention to the guy in the shop that you're climbing hills. That makes a little bit of difference in the optimal height of the saddle.
It doesn't sound like you're at the point where you need to worry about serious training. Focus on gradually getting your distance up.
What distance do you comfortably ride now?