Almost every plant here has thorns. I end up changing tubes a number of time a year. I practiced at home a couple of times first. I was really suprised and how easy it was. I always had problems patching the tubes so I would have to go and buy a new one. A couple of months ago I learned how to set the patch properly....apparently ya shouldn't touch the glue to see if it is dry.
I haven't tried the leverless method yet.

The worst time I had changing a tube: 25 degrees, just dawn, tube melted or frozen to the inside of the tire. I had to completely remove the tire to rip the tube out. My commute is short so I don't dress really warm. My hands and feet were like icicles by the time I was back on the road again.