How to know if you’re dilating...

Sorry if this is such a dumb question BUT...

I’m from the U.K. and unlike the US we don’t have appointments to check for dilation and things. I don’t want to ramble on but I basically want to know if there is a way to tell if you’re dilating other than someone checking?

(Don’t worry I won’t be checking myself as I know that can cause infection) but would I experience any symptoms or anything? I read someone’s post earlier and at 35 weeks she is 3cm dilated! I’m 35 weeks and wondered if I could be dilating?