Best way to get used to skidding is to just put your junk to the stem and lock the legs. I know it can feel super scary at first, but you just gotta do it. Start out like that and then you'll get comfortable with your timing to lock your legs, and you won't have to lean so far forward eventually and you'll be able to do seated skids. It's good to mix up all techniques of stopping. I ride 48x17 (just switched up from 42x16) and I back pedal, or resist, a lot when I have time to, skid sometimes just for fun or to check my speed down a bridge or hill, and also rock a front brake for the "oh sh*t!" moments. Just always look ahead at an intersection you're coming up on, or traffic light, or anything at all. Most important thing is to be aware of what's ahead of you and allow plenty of time for stopping and reaction. There's also what some people call "ghost pedaling" or any other name you might hear for just letting your legs rest in the pedals, no forward or backward motion, kind of like coasting to a stop.

You'll develop your own style and comfort level the more you ride, just spend as much time on your bike as possible and get used to it and comfortable and it will be like second nature before you know it. You can even set up fake scenarios when you're on a nice open road or parking lot, like pretend a certain line in the road is a car that just whipped out in front of you, or a light that changed, and practice stopping at that point. I know it may sound corny, but it's good to know you can handle all situations to fully enjoy your bike and ride confidently. Hospitals are overrated. Hope this helped some, and enjoy your bike!

(and at risk of sounding redundant or repetitive with everyone else, but definitely invest in a front brake haha)