Moving photos from old phone to new

I've a bit of a conundrum with photos and moving them to a new iPhone 8.

I have the bog standard 5Gb iCloud for the backups, and that has worked fine, the new iPhone 8 was restored with the apps and data from the old iPhone.

The problem is, the photos are too big to fit onto iCloud (despite deleting a load, including videos), so I can't seem to transfer them to the new phone this way. I plugged the old phone into the computer, transferred them over to the PC, but when I plug in the iPhone 8, it's read-only, I can't copy the photos from the PC to the phone.

Aside from paying for the increased capacity on iCloud, is there a better way of transferring the photos from the old phone to the new?