Norton 360 renewal due soon. Confused

I have Norton 360 on my lap-top p.c. which i have updated to windows 10 and all is working fine. 

My Norton 360 subscription expires in 18 days and I have had an email and a couple of pop-up messages inviting me to renew, as well as on the Norton user interface. (The screen with the green squares where you do scans etc.)

Having read on here about 360 being replace by Norton Security I am not sure what the best course of action to take is.

Should I uninstall my existing "Norton 360" and install "Norton Security", basic version as I only use the one device and don't use the 360 back-up storage facility. Alternatively, if I respond to one of the reminders to renew will it give me that option or actually renew the 360 as some replies on here seem to suggest?

Also if I save a few pounds by buying a product key number from my local P.C.World store for "Norton Security" would I be able to use that in the renewing process from my existing Norton user interface or one of the other reminders?

You will have realised I am not a computer expert and like to keep things as simple as possible.

Thanks.

Frank