Please can someone help me get my edited photos and videos from my phone to my computer?

If you have the photos in Photos on the Mac, select them in the Library then choose File > Export > Export n Photos…

The next dialog will allow you to choose the output format, size and other properties and you can then save the exported photos in your chosen location and transfer them to your own computer by any file sharing method.

Alternatively, depending on how many photos you need to transfer, you can select them in Photos on the iPhone and AirDrop them to the Mac, which should preserve the HEIC format - you may need to check whether this includes any edits you made on the iPhone or not, though.

Finally you could also email them from the iPhone, or add them to an iCloud photo album from which you can then download them to the other computer. If you have other apps installed on the iPhone that can be used for sharing images then they may also appear as options here; for example, I see Flickr and Evernote. If you have Dropbox you can upload photos there from within the Dropbox app.