if you buy a wireless access point you can plug it into the network cable and it will enable wireless in your cabin.
Bongo, do you mean run a cable from the router to the cabin and then plug the wireless access point into the cable?
Yes, exactly
Not using repeater mode as I doubt there's a suitable place to plonk the access point to get signal from the router and give it to the cabin.
I'm old fashioned though, I like wires... they work!