When you say Rules, are you talking about site Rules like "keep you plot cultivated and weed free", that kind of thing? I ask because society constitutions can also be referred to as Rules so it can be a bit confusing.
I'll assume you're talking about the enforceability of the site Rules.
Short answer is that the association constitution is a red herring, but you need the long answer, so can you clarify a few things for me:
1. Your site association manages the site, right?
2. Is the association unincorporated?
3. Who owns the lease on the site?
4. Do you manage the site under some kind of management agreement?
5. Do you manage the site on behalf of a council, or is it private?
6. Can you say if the allotment acts apply?
7. Does your tenant have a written tenancy agreement?
8. Are the Rules incorporated into the tenancy agreement?
9. What are the Rules that the tenant refuses to comply with, and why does she refuse?
10. Have you served any kind of notice on the tenat requiring her to comply?
Sorry, you've asked a complicated question.