HUZZAH!!! For anyone else having a similar issue to me then you need to check your firewall and allow NzbDrone through it. I was looking for Sonarr and Radarr, which weren't on the list, but then I recognised NzbDrone and altered it from private to public.
Thanks to the guys of NZB360 for all the help tonight. I'll tackle how to access remotely another day but for now i'm chuffed because this app is just awesome!!