What andy7t2 says is all true. What he doesn’t say is that once you’ve got all the paperwork done, got your crb back and recce’d a few routes you’re pretty much set up. Yes, you’ll have to do risk assesments for every ride but these are pretty much generic from ride to ride.
Regarding quals, I’ve got MIAS level 2 and have yet to find anyone to tell me that’s not enough. There’ll be plenty of folk, on here and elsewhere, that’ll tell you there are much better qualifications out there but they can take up to 6 months for you to get qualified and let’s face it, if you’re good at the job does the standard of the qualification matter?
Not sure where you are but raymazey on here runs a 2 day course in Bolton that’ll get you MIAS level 2 qualified, providing you pass obviously.