function redirect_to_forum() {
	global $bp;
	
	$path = clean_url( $_SERVER['REQUEST_URI'] );
	
	$path = apply_filters( 'bp_uri', $path );
	
	if ( bp_is_group_home() && strpos( $path, $bp->bp_options_nav['groups']['home']['slug'] ) === false )
		bp_core_redirect( $path . $bp->bp_options_nav['groups']['forum']['slug'] . '/' );
}
add_action( 'wp', 'redirect_to_forum' );