will Heliamphora nutans x heterodoxa grow ok in a greenhouse environment heated to a minimum of about 5c in winter and upto 30c in summer in full sun. or will it be beter growing them with my neps?

Yes, that particular horticultural hybrid is on the tougher side and will easily survive those conditions -- and more. Just try to ensure that the plant gets regularly misted or is in a tray when Tbs soar beyond 30˚. Far better that it receive full sun for color and leaf development. Far too many Heliamphora are light-starved . . .