Best UX for purchasing event services through store?

Site URL: https://www.walkingadelaide.com.au

I have a client who sells networking walks - individual, 3 walks, 5 walks, 10 walks and an annual package.

They're after the option for someone to INSTANTLY be able to pick the 3 walks they want when selecting the 3 walk package. I can only see this happening through a created order form? The UX journey for myself is confusing.

They originally want people to complete a form and purchase within that form (which I wish could happen).

Any ideas or concepts? Would rather not use 3rd party apps like Eventbrite - but also I don't think they will want to use Members Area or Scheduling. 

Hi,

Have you ever collected any good options for this?

I'd gone with the form and express checkout option.. it's currently live if you click that link to see!