Talk

First check what is taking up the space. Settings / General / iPhone Storage is how to do it on the latest version. It’ll show the space used by photos, apps and so on.

You’ll want to get those photos off the phone and to a computer, instructions for that are here:
support.apple.com/en-us/HT201302

Podcasts took up a lot of space on my phone. They were set up to download automatically.

Thank you.
I have no podcasts.
Just photos

I'm the same op. I have iCloud and I think I've got to do a back up on my pc to iCloud and then I can delete them off of my phone.

You can use the iCloud Photo Library to help, but it will still use space on your device, though it can be told to try and be clever. Details here:
support.apple.com/en-gb/HT204264

You also only get 5GB with the free iCloud, and that’s not much when phones can hold more than that. So you’ll end up having to buy space.

I find the best way is to download them onto a computer and delete them from the phone. Details for that are in the first link.

Download the google photos app and sync the photos. You can then delete them from your phone.