In my experience it depends on the mileage you do, but VW should quote you basing it on your miles.
I had it with my previous 2015 Vivaro, and it worked ok to start with, but then I ended up reaching the service schedules faster than i'd paid for them.
Vauxhall did give you a favourable price for servicing with a service plan, but I didn't get that far in the conversation with my VW guy, because the quote they came back with was bonkers, because of the high miles I can do in a year.
Bare in mind I couldn't move my service plan to another main dealer, and if you have a bad experience with your current dealer, which is entirely possible, you might be stuck with using them for servicing. So ask the question about moving plans to other dealers if necessary.