This is the second post in this thread that has hinted that it would be ok to go to an established, but not managed by a formal club, flying site without approval of the people in charge of the site. Fortunately, RJM has already responded that he knows better than this. However, for the benefit of others, here are my thoughts on the subject:

If there is a group of people who has established a formal or informal relationship with the owner of a flying site, this relationship must be respected. The rules and policies of the flyers who have permission to use the facility to use the site must be followed. Ignoring these rules, such as flying alone there before being signed off, should never be done. Any individual contemplating such action needs to realize that doing so could very easily result in a situation where the flying site is lost to EVERYONE!