Thankyou so much for all this advice!
Had my first treatment yesterday and decided to try coldcapping
Coincidentally there was a guy there doing staff training from the company who asked if he could use me to demo exactly how it goes on.
He was lovely but VERY determined and did end up feeling slightly wrestled with but it was certainly thoroughly in place! I think the nurses were a bit discombobulated, (‘we try to be very gentle,’) they told me as they forgot to switch me on at first and I was sitting there for a while thinking ‘well this is going to be ridiculously easy’ 
Once it was on it certainly was a challenge for the first half hour or so but after that kind of ok (I had it on for 3 hours) I am really glad I decided to give it a go, but need to get some different earphones that will work with it for next time as I need my audiobook!