OK, so after asking cavers (for a Hidden Earth competition) to show they have UKC added to their mobile home screen, turns out iphones do it differently.
I don't own one so can't post a screenshot - any kind soul that can please help, thanks.
Google ukcaving, single the webpage, open it then....
At the bottom of an iPhone screen is a square with an arrow in it pointing upwards. Press that - more features pop up, scroll through them until you find 'add to home screen', follow directions.
Feel free to improve on this post and do let me know of any successes. I'll add to the original post once I have the best description.
Thanks, Pegasus