The only other tiny critter that I can think of that might fit the description (just) are thrips and these can damage plants. However they are not soil dwelling, so don't worry.
If I lived in the USA instead of England I would ask you to post me some, preferably dead in alcohol. But there are really strict rules about doing things like this, so it's not worth the expense and bother.
A trip to you local high school/ college/ university should provide someone with enough expertise to ID these bugs, you only need to know which order they are in, not which species.
If they are not causing any obvious damage symptoms, I'd just let them be, they are just a natural componant of your soil, feeding I suspect, on microbes and fungi, and doing more good than harm. In their natural habitat, Nepenthes coexist with thousands of different soil dwelling creatures quite happily.
Vic