i played and beat a chaos army that was all hand to hand, this is what i did, i loaded up 2 full squads of boyz and suped the nob up with mega armor and a megabooster, with his powerclaw he could take down on average 2 chaos guys at a time, the boyz just basically absorbed the brunt of it and took some heavy damage, i would work more on gettin gthe 2 troops to do the most damage, if you march them one at a time and rush the second group into combat after the first assaults you'll have 2 nobs in there doing some damage : )
other then that get lucky with rolls and don't feild a big HQ