thinking about it, if there is such a thing as an FA arbitration panel then it is probably the case that in granting clubs licences the FA required every club to include an arbitration agreement in all of the contracts with players. it is probably the case that if the player refuses to agree to an arbitration clause, then they can not have a contract due to the club's obligations to the FA. every players' contract for every club probably includes the same arbitration clause which states that the parties can refer to dispute to the FA for it to appoint an arbitrator or panel of arbitrators (an arbitral tribunal).