Ashford Allotments' do have a Facebook page, anybody can join, but it's not compulsory and it's not used much, other than as a helpful chat forum tbh.
The council has the email address of anybody that wants to give them their details, but again it's not compulsory. If the council wants to tell tenants something and they're not on the email list then they get a letter.
In a normal year, the site reps and the council reps meet every 3 months or so to discuss matters arising. Plot holders can attend the AGM to meet reps and council, if they want, to discuss anything they haven't told their reps about previously...