Section 19 permit

Hi folks,

Sorry for the stupid question, I drive a school bus operated on a sec. 19 permit. On the D1 part of my license, Hrs are Mon. to Fri. 8am till 9am… 3pm till 4:30pm total of 2.5hrs. per day.
I have been offered PSV work driving airport shuttle bus a route abt 2km in total. I cannot figure out what I can drive at the week-end as I understand both
jobs are outwith uk driving rules or exempt. ■■?