Most schools now have virtual tours and information available on their website.
In-person tours, where I can find information about them, appear below.
Open days and evenings for local selective independent schools:
Birmingham Consortium Schools
Dates will presumably be published here once set.
Other schools
Queen Mary's High School (Girls)
Queen Mary's Grammar School (Boys)
Alcester Grammar School
Stratford Upon Avon Grammar School for Girls
King Edward VI Stratford Upon Avon (Boys)