Re: I face a dilemma.
Why are you using Skype on iOS? You have Facetime.
Thanks for the useful suggestions. I agree re Facetime - it's good, reliable, uncluttered, and doesn't assume that I'm a tween girl incapable of expressing myself other than in emoji pictograms (albeit as someone said further down in this thread, it does seem to need higher bandwidth).
However, it assumes - correct me if I'm wrong - that both parties are on Apple devices. I'm on an iPhone, but my friends in England are on a PC and a steam-powered featurephone.
Cheers to those who recommended Signal (I've upvoted you) - will check that out.