Would this be the website from my screen shot below, where i had no difficulty accessing using my Android Tablet.
Apart from my Broadband Buddy is set to age rating of 18 the only changes i have done to my NOW Hub 2 Router is split the two wifi frequency bands and disabled IPV 6.
I managed to find website in question and it's a no go for me also where both my tablet and smartphone just hangs there.
The message i get is "This site can't be reached" error timed out.
Couldn't tell what this website is about.
Maybe drop NOW an email with a link to this thread if you think that this website shouldn't be blocked by them for any reason.
Otherwise if you haven't got all inclusive mobile data on your smartphone or not prepared to use it for inconvenience reasons purely to access this website, then advise the NOW Broadband Team that you are looking at an alternative ISP.
Use the email address in this screen show below to contact them.