Rake it! Or, if it's really hard, fork it gently and then rake. The rain we've had (which now, blissfully, feels like a distant memory) will mean there's probably a layer of pretty damp, darker earth just below the surface. Plus, it needs to be well-raked anyway for the turf. Lots of people put down a top layer of sandy topsoil before laying turf, so that's another option. But I think I'd want to break it up to make sure roots could get into it, IYSWIM.
You will need to water it a lot in this weather! I might be tempted to leave it til Sunday, after which rain is predicted for a few days, significantly reducing your water bill!
Wolf Garten tools, that have various 'heads' to fit onto different length handles, are very effective at breaking up and conditioning 'difficult' soil. They may be more expensive than 'normal' tools, but can be the best solution in some situations.