Ironfromafar, there are many ways but the way that I do it is through my laptop (log on via a VPN coming from a non UK country if you want to get around the UEFA Article 48 regulation not that I would encourage anyone to disrespect any UEFA regulation).
Buy the game via http://www.nationalleaguetv.com and connect your laptop to your brand spanking new TV via an HDMI cable (I am assuming that both the laptop and the TV have an HDMI port).
I am also assuming that as it is on the SUFC website that the National League TV service will start broadcasting our games from the National League North.