If you want to pre-plan your photos you can find more information
about the fort here: https://royalarmouries.org/venue/fort-nelson/
Entry is free and as you can see from the below there should be lots
to explore with plenty of photo opportunities. There is a fee for parking
unless you park opposite which is free. Remember no tripods but flash
is fine.

https://goo.gl/maps/hKNpuUWL5CgBNPNB8