How can you build a prototype without the information in the standards that tells you the limits to how you design your prototype?

You are going to have many iterations after that first prototype. Your looking for proof of concept here and some early user testing, a long way to product yet; basically enough detail to know the right questions to ask.

Spend GP's €200 on some time with a consultant who has already read them.

Just do it all again when you get customers, which you can only get after your’re actually approved for business, for which you need the standards.

I guess maybe you can just ‘hope’ you comply and let the inspection figure it out if they ever show up.