"It's going to be a mess, and there really does need to be some kind of grace period where companies can get caught and told to sort things out, but not necessarily get stung for the fine, because those fines could cause some serious damage if they're doled out to every offender from day one."
In practice regulators aren't going to be able to follow up all complaints so they'll have to make choices. Hopefully it'll be a case of chase a few particularly egregious examples first and have a warning letter system for the small fry. When they have the resources they can then follow up on the warning letters and see if they've got into compliance.
But on the wider issue of not being aware etc. companies, charities, societies etc. generally have a good idea of the accounting, statutory reporting and other rules that apply to them. When you ignore the hype this is just another of those rule sets to be incorporated into BAU. As with the other rules some organisations will fail, deliberately or otherwise; of those that fail some, as with the other rules, will get lucky and not be caught while others are penalised. It will all become the new normal.