i don’t have a wifi connection is it possible to update using my mobile data.

Wi-Fi is required.

Park outside a Macdonalds and borrow theirs.

Not really. Your only other alternative is to update through a computer, but then the computer will require an ethernet connection to the internet. See the 'Update your device wirelessly' and 'Update your device using your computer' sections in:

Update your iPhone, iPad, or iPod touch - Apple Support