My dd is also coming from a state primary with no guidance or help. I was quite worried after the exams during the long wait, but my dd got to the interview stages, so I felt a little less worried. However, the chances are only 50% (it seems anyway!) once you reach the interview stage, so still a little worried. Do other kids at your dc school also do 11+? My dd only knew of 2 other dc, not really her friends so it felt like no one was doing it.
Someone I know who has a daughter in a selective prep said its a tough year because of the strong cohort. Many spent the lockdown studying for the 11+ (at her school anyway). Others have mentioned higher birthrate as well.