is this product ok with under floor electric heating please
Yes. This product can be used with underfloor heating. The heating device should be installed on top of the tray.
It is based on XPS which is good insulator against sound and warmth, therefore if it was installed under the board it would limit the warmth that could go through the tray.
Please notice that the vertical frame of the drain integrated with that tray is 15 mm and that's the space to fit your tiles, tile adhesive and underfloor heating into.
That can go slightly above the frame, never under. If your total material is much thicker than 15 mm we have another tray, we call it Invisible, it doesn't have any restriction about finish material thickness, although it has other - must be covered with it entirely.