Do two passes.

First collect all old files and dirs in an array, and then delete.

#!/usr/bin/perl
use strict;
use warnings;
use File::Find;

my $limit = 180;

my @files;
my @dirs;

find (sub {
    if ($limit < -M) {    
        if (-d) {
            push @dirs, $File::Find::name;
        } else {
            push @files, $File::Find::name;
        }
    }
}, "/my.co.uk/video/testdelete/");

unlink or die "$_: $!" for (@files);
rmdir or die "$_: $!" for reverse @dirs;
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