Cannot setup Cellular on new Iwatch5

Ive purchased the new Iwatch5 and have paired it to my IphoneX. I have added the $5 monthly charge by Vodaphone linked to my Iwatch to make use of the Cellular feature however cannot get this to work.

My phone and watch only work together when within range. Ive checked all settings and the only option that I cant seem to find is the 'cellular' option on the watch app on my Phone. Thanks in advance for any tips, Alex