Hmm hello paulhdear and welcome to the forum..
Well your first instincts are right, they for sure have found a place out of sight, and your right not to go digging for them, i do not think that they will be dead, i would assume they are where the heat source is, they will only go into hibernation if the circumstances are right, and as you are providing heat for them, and light, its likely they will not. I assume you have been feeding them, have they been feeding well, I ask this only to determine if your able to wind them down and let them hibernate if only for a few weeks, all you need to do is, keep the light off and turn the heater down maybe over a 2 day period, then put them somewhere cold, (i personally have put my colony up in my loft, which has worked a treat,)and then all you need do is just add fresh water and maybe some suger/honey now and then, disturbing them little, and then you can wake them up again in a few 4-5 weeks time, then yuor queen will start work on building her colony, I think i have coverd most things here, but there will be others to guide in anything i have mist. I hope i have helped a little.
