Coolant keep dropping and Engine isn't receiving any coolant.

[Snookesey]

Hello! 

I have had a bit of an issue with my 2012 Ford Fiesta recently in that my coolant Level keeps dropping. On closer inspection, I couldn't see any external leaks i.e. Coolant on the ground under my car or around the coolant pipes. I took the car to the garage who told me after looking it over, that there is no coolant getting to the engine at all, which would explain why it has felt so hot despite me refilling coolant reservoir frequently.

Does anyone have an idea what might be the issue here? I am thinking there may be an issue with the thermostat (stuck in the closed position and so preventing coolant from reaching the engine?), but I'm not too sure in all honesty.

I have to drive from Lancaster to Shropshire (just under a 2 hour journey) on Sunday as I'm coming back home from University so any advice/help/experience with this issue would be greatly appreciated.