You cannot attend a Single Justice hearing. They are held in an office with a single magistrate, assisted by a Legal Advisor, adjudicating in cases "on papers" only. Nobody else can attend.
When you responded to the Single Justice Procedure Notice there would have been three options:
1. Plead guilty but do not attend court
2. Plead guilty and attend court
3. Plead Not Guilty.
Only if you chose option 2 would your case have been listed for a hearing in the normal magistrates court.
However, as I said, your speed is well into the range where a ban might be considered. If the Single Justice believes that it should, your case will be adjourned and listed for a normal hearing, which you will be invited to attend. The Single Justice will not ban you in your absence. If he SJ does not believe a ban should be considered you will simply be advised of the outcome by post.