As you have used the term "community council" I am assuming you are referring to a council that is based in Wales. Rules for Welsh councils are slightly different from England and I am less familiar with the Welsh requirements but a couple of things immediately spring to mind. Firstly, not being aware of a meeting and details not being published might be different things. I believe community councils are required to publish details of meetings both electronically and "in a conspicuous place within the parish". Are you saying both notices were absent? As a general principal in England at least, a defect in the notice of a meeting does not necessarily render decision taken at that meeting invalid. So, for example, in England if the council's website fails or perhaps the notice of meeting can't be posted on the notice boards because of flooding then the meeting is still valid, albeit it is a situation which is not ideal.