I think you should do both! And is skating hard? When you first start it may be, but after a few days you will start to feel comfortable on the board, and you will be able to start doing tricks. You should probably not go to the skatepark straight away, unless you can do a few basic tricks, such as the ollie.
Maybe you should surf when the waves are good, and skate the rest of the time? When buying a skateboard, make sure to get one that is over $100, as quality is important. If you buy anything less than that, you will probably just end up having to get it replaced. Also, don't skate when it is wet, because you will ruin your bearings!
I hope that helped,