My advice to Tom, and anyone else facing this problem, is to do something else for a while. I don't mean to stop skating, but do some other stuff. Just cruise around for a while. Find a parking lot and simply ride around, cutting wide turns. Get relaxed, and clock some hours on your skateboard. Practice things like kickturns, and tic-tacing. Push really hard and get going fast down a sidewalk. Cruise casually for several blocks. Get good at stopping, and learn a few different ways to do it.
The point of all of this is to get COMFORTABLE on that skateboard. You need to feel like riding your skateboard is comfortable. A lot of fear comes from simply rushing too fast. Some skaters are fearless and can learn to ollie the first day they get on a skateboard. For them, that seems natural. These are often the same skaters who will probably get hurt a lot! Fear has a real purpose, and it's not ridiculous to be afraid of skateboarding! The cure, however, is often to simply skate and skate and skate. Every day. As much as possible. Ride that thing around everywhere you can.
You can also try other tricks that don't involve popping. Try manuals! Skate some flow at your local skatepark. Try dropping in (though that might be scary too - it's OK!). Spend a lot of time simply playing and relaxed skating on your skateboard.
Now... there's one other thing that might happen through all of this, that can be a BIG help. You might also need to simply fall down a few times. And if you clock all these hours skating that I'm suggesting, then you might get that opportunity! Skateboarding can be a painful thing to do. That's just the way it is! But the pain isn't THAT bad! Wear a helmet, always, but you can also wear all kinds of other pads if you want. I wore knee pads for a long while when I was learning to skate. That's street skating, mind you. No need for knee pads at all! But, they gave me confidence. I had all kinds of pads, and it helped me feel better. But the real trick came when one day I was trying to learn how to ollie, and I was standing in the driveway, and my stupid brother gave me horrible advice. He said, "Just slam the tail down, and see what happens!" I said, "OK!", did it, and the board shot out across the street. Meanwhile my feet went with it, and I ended up sort of laying sideways in the air, and slammed HARD. I jacked up my wrist for weeks, my hip had a huge bruise and was bleeding, and my shoulder KILLED me for DAYS. I think I called my brother some creative names, went and got my skateboard, and stomped back into the house... however... I healed. I got better, and the next time I was a little more fearless. I knew what to expect, and it wasn't that bad!
So my point with that little story is to say, don't be afraid to get hurt. Getting hurt can make everything easier! Wear a helmet and you will be fine.
My last little piece of wisdom is to remember that being afraid of getting hurt means that you are SMART. Getting hurt sucks! It's not fun, but you will be OK.