Thank you all, this is reassuring.

I understand the idea that it might, in some situations, become a very good idea to have an epi, depending on how the labour goes and how I deal with it. I'm not one to get very intensely committed to an idea of a "perfect birth" - anything that leaves me and baby healthy is good enough!

But I'm very much planning to not plan for any intervention, and in fact to resist suggestions for interventions that might not be necessary. Which is why the stuff I was reading earlier was worrying me.