Investigating floor structure without damaging DPM

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I am hoping to have UFH installed when my kitchen/dining room is renovated. For this UFH installation I would be keen to have:
- adequate insulation to maximise the efficiency of the system and minimise heat loss
- maintain the floor level so as to have a consistent floor level with the rest of the ground floor.

I suspect this would involve removing the current slab and digging down to create space to install new slab, insulation, ufh and screed, although I know this would be costly.

I don't know the specification of the current floor to see what the current situation, and whether there are some more pragmatic options and had read about drilling a hole to explore it.

I was wondering how one approaches drilling such a hole without risking going through the dpm?

Thanks for your help