I'm in the US, so they are easy for me to buy, not sure where you can find them.
They are easy to use but you should do a few practice runs. I hated them for AF as they leaked. But they don't leak after BD'ing for me. When you practice, don't do it during AF, it can be messy.
They have a good tutorial on the Instead Softcups website. https://www.softcup.com/video.html
The first few tries I had a hard time getting them out. But then I read that you could bear down (like giving birth or having a bowel movement) and grab it while you bear down. It popped right out for me. That is the easiest way for me to get them out. And no, they absolutely can't get lost and I think would be very hard to get stuck. Good luck! This is my second cycle using them. Hope they worked this time around!