I cant charge my iPhone SE, if I switch it off and then plug in it comes on, so its getting power but not charging, can anyone help please?

If you aren’t seeing the lightning symbol over the battery icon, then you are not connected to power. You need to determine what is going wrong. Check the port for lint. Try a different cable if possible.

It is doing what it normally would do. If you turn it off before plugging in the charging cable, it will turn on when you connect it. Even though it is on, it will still charge the phone. If you want it off, you need to turn it off after you connect it to power.