There are a few possible solutions to this listed across the web none of which worked for me personally but I’m gonna list as there’s always the chance they’ll work for you.

Firstly try getting the network to reconnect by switching flight mode on and then off again.

Secondly perform a full reset (holding home button and lock button together) and reboot.

If, like me, none of these settings work for you you can try the following which sorted it. Navigate to the Cellular Data page by going to Settings > General > Network > Cellular Data Network.

Once here you may notice that there are a few fields here with missing information, it turns out that the update seems to wipe these on occasion. All you have to do is insert the following details in the relevant fields. (Please not these settings are for O2 customers)

Cellular Data

APN – idata.o2.co.uk
Username – vertigo
Password – password

MMS

APN – idata.o2.co.uk
Username – vertigo
Password – password

Hopefully these should help restore the internet connection and get you back up and browsing in no time. If you have anything to add let me know in the comments.