while (<DATA>) {
    # lol, comments in __DATA__ :)
    next if m/^#/;

    #m!! to allow for better-readable slashes inside the regex
    #/x modifier to make the regex even better readable

    ($date, $address) = $_ =~  m! .*? (\d+ / \d+ / \d+)? \s* (.+) !x; 
    print "date:<$date>\naddress:<$address>\n\n";

}

__DATA__
# a line without a date
                A very good looking address
# a line with a date
15/5/85         That's my actual birth day!