Meetings of the Council and of its committees are formal events, hopefully friendly, but still not social events in themselves. They have a clear purpose which is to make decisions, they are not simple opportunities to exchange information.
All meetings are open to the press and public unless they are specifically excluded by resolution of the meeting due to the confidential nature of the business. These exclusions should be few and far between.
Committees may be permanent (such as finance or planning) or may be set up to deal with a specific issue or project and then disbanded afterwards. Committees may have decision making powers afforded to them by the council or may only be advisory. The council will decide which it is.
Local councils are obliged to hold an Annual Meeting in May (or in an election year within 14 days of the election) and must also hold a Parish/Town meeting. This is a meeting for the electors of the parish or town to meet and speak about matters of interest. They also afford the council the opportunity to speak about what achievements they have made over the year.
In addition the Council must hold 3 other meetings (as a minimum). Some councils meet monthly, some bi-monthly, it is up to each individual council to decide on what frequency is necessary.
For details on how committees are set up one would need to look to the council's own Standing Orders which should be published on their website or be available from the Clerk. ChALC provides the model standing orders which councils can then personalise.