Right. You can buy a boat. No questions asked, You can insure it or not. You can drive it on the sea, most anywhere. There are no laws so far about the sea. However. Harbour masters have laws and other folk to.

I have nearly no qualifications, just learned the hard way. Yes you can get a course for the basics, or higher , or higher.

I'd google sites to find a course..

So, you need nothing to go to sea. Other folk might not let you out on there boat though.

I learned as I went on. But was lucky enough to miss the rocks. Duno, hows your feelings.