This song is driving me mad! Its used on Homes under the hammer and there is a 12 second clip here: http://www.burnsville.freeserve.co.uk/huth1.wa v Its poor quality I'm afraid but I hope it wil be sufficient if you know the song Cheers PS its not Express Yourself by Charles Wright!
It's a short sample, but it could be 'Express Yourself' by NWA from their album Straight Outta Compton, which samples Charles Wright's tune but funks it up a bit. And of course they rap over the top....