The best place to go for some shut-eye is the T5B Galleries Club lounge. Study the Passageway guide so you know how to get out from there, but your onward flight maybe nearby anyway. Ignore the signs telling you not to go to B until your flight is called. The far corners of the lounge, which is quite a reasonable size, sometimes get no visitors all day long.

When you are not sleeping, use the time to find a new employer.