K FED'S MEAL TICKET!

Babysitter-of-the-year Kevin Federline blew some of the $30K Britney's paying him to watch the kids this month on a quality dinner in London last night -- at the local Hard Rock Cafe.
Federline rolled into the joint with the bodyguard seen in the photo -- plus his GF and a personal nanny to help with little Sean Preston and Jayden James.

It's great to see K-Fed finally holding down a job.