You get an Oxford book of plain English at the law school I went to!
Lawyers only have contract terms or laws/rules to work with. That's why so much effort goes into the drafting of the terms...
Ambiguity is usually settled by "persuasive" material that may help interpret such rules, usually minutes of meetings where decisions were taken (Hansard for parliamentary debating) and guidance material. In a contract, the rules are what is signed or agreed. Rule 7 is without guidance on the face of it, so unless this guidance was made available as part of the details given to a club they could easily argue the meaning of what the words purport to say.
What's obvious to you may not be if you think about it. If I said you have 7 days to think about it and consider the answer, do I mean 7 days from midnight, from the time I say this post, the time you read it, and does that include weekends?
Tax law is the best example of the power of words... There is NO given right for the state to tax, so they can only take your cash if they legislate for when. Lawyers then argue what the words mean - fortunes were spent on deciding if a Jaffa cake was a cake of a biscuit! Why? One is taxable for VAT.
Solicitors are taught that the dictionary is the starting point, but look up cake and biscuit and work out which is a Jaffa cake! Apply that to "concessions" and must be "available" and see what it could mean if you think widely.