With multiple e-mail forwarding you can have up to 20 e-mail addresses of the form xxx@your_domain.co.uk and have each forwarded to a different existing e-mail address.
Examples would be:
sales@xyz.co.uk
forwarded to joebloggs@freeserve.net
info@xyz.co.uk forwarded to fredbloggs@virgin.net
james.harding@xyz.co.uk forwarded to jharding@thebeeb.net
You can change these as often as you find necessary at no additional cost.