Catrin, I couldn't connect to the link from Performance (an error on their part), but I assume you are talking about the dual sided "campus pedals" that are flat on one side and spd on the other. I wouldn't recommend those for a beginner. The problem is they flip over/around when you are clipping in; not something a beginner wants. Obviously you can keep pedaling on the flat side, but it's annoying. Having the flat side weights the pedal, causing this to happen.
I have these on my hybrid and mountain bike. It's fine for the mountain bike, since I stay clipped out on one foot a good deal of the time!! But, I rarely ride in regular shoes on the hybrid. I use that bike to do errands and occasionally for destination rides, or on casual vacations. I find that like you, I have forgotten how to ride without being clipped in. After an embarrassing experience commuting to the train station last year, the only place I ride in regular shoes is the one mile to the pond in my neighborhood.
I started with dual sided spds on my road bike 9 years ago, and used those for a year until I got a new bike and got Speedplays. I'd stick to the dual sided ones.