THEY WILL BE serving coffee and danish, but it will be a rare love feast of local political figures on hand shortly before 8 in the Capital Hilton this morning -- eager to join any interested community leaders in a unified, fresh and realistic quest for more self-government and voting rights in the District of Columbia. Finally -- after so much time feuding and fumbling over who gets center-stage, and for what cause in the name of "home rule" -- the various actors apparently are ready to take stock of all efforts in Congress and around the country to shore up the District's authority and ability to take care of itself. If so, there is serious work to be done -- and a chance of serious results.

This meeting, called by Mayor Barry in concert with practically every other local political figure you can think of, is not just another rally for ratification of the D.C. voting rights amendment -- through this campaign is by no means dead yet. In addition to enlisting specific help in that drive, the participants are talking about broadening the movement to include all aspects of a fresh "home rule" campaign -- from improvements in federal payment process, to more local control of the city budget, judicial autonomy and other ways to make a more efficient and self-sustaining jurisdiction.

Whatever else it may or may not prove, the voting rights ratification effort has provided -- and continues to afford -- an opportunity to build some understanding in the states of the District's struggle for political equality. But opportunity is one thing, opportunism another -- and there's been an overdose of the latter up to now. The case for full representation in Congress for Americans who live in this city is one of simple justice, even though the message has been drowning in seas of ignorance, polluted by diversionary talk about race, partisan makeup and rurual-urban "balance."

In any event, there are 14 states in which attention needs to be focused on the voting rights amendment in 1981. And there is Congress, where any lists of other improvements in the home rule charter must go for scrutiny and understanding. Here, too, understanding on the Hill requires and educational effort as well as demonstration of local unity on behalf of changes.The mayor, members of the council from all three parties, Del. Walter Fauntroy, Republican and Democratic members of Congress and business leaders all see the merits of this regrouping. But to work, it must enjoy concrete support from the broadest possible spectrum of community groups.