Use a bit of lateral thinking to solve your problems. Here are some examples...
Although there's no hard-wired way of doing this in Driver Planner you can achieve it by creating five (or seven) ficticious Attendees called Reserve - Monday, Reserve - Tuesday and so on, with the Monday Reserve set to attend on a Monday, the Tuesday Reserve set to attend on a Tuesday and so on. They will then appear in the diary each day as an "unallocated attendee" and you can allocate a driver to them just like any other attendee.
If you've got a list of drivers who provide transport but you also want to pick some attendees up by Taxi, Ambulance or whatever, simply add a driver called Taxi or Ambulance who is set to be available every day. You can then allocate the Taxi or Ambulance to the attendees who will be transported in that way.
If you have people due to attend or be visited on a Monday and it just happens to be a bank holiday, you might want to move some of them to the Friday before and some to the Tuesday after. It's quite easy to achieve, just go to the bank holiday Monday in the Diary and right-click on each person in turn and choose Move forward to... Tuesday or Move backwards to... Friday until you have moved everyone out of Monday onto other days. This one-off alteration doesn't affect their regular attendance pattern in any way.