Rover 75(1.8) Broke down on M5-no water in engine-is the car now scrap?

[andybilston]

I was driving on the M5 when I sensed a slight smell of burning but wasn't sure if it my car or not. I was driving on the 4 live lane section where there is no hard shoulder so had to carry on for a while before I could pull over. As I was pulling over onto hard shoulder the car seemed to be shaking a bit and a small amount of steam came from engine and it then cut out.
The radiator was out of coolant and a hose and part next to engine block was melted.
The RAC came out and confirmed it was out of coolant and the engine is terminal. The car is now sat outside my house.
Not sure what happened as I always check all the fluids regularly and everything seemed ok.
I had a new coolant temperature sensor fitted a couple of weeks ago as it was intermitantly running cold but all was good after it was fitted.
Can I assume that the engine is now totally useless and beyond repair and that the car needs to be scrapped or is it worth trying to repair it?
It's the dodgy 1.8 engine in it.

Thanks
Andy