Dartmoor gets a lot of weird light activity so I'm probably immune at this point, but missing time is a different beast entirely. What stretch of highway was it? That detail matters more than people think - certain corridors seem to have repeat incidents and if yours lines up with known hotspots that's not nothing.
How long was the gap roughly? Under an hour is often written off as dissociation or microsleep but anything over two hours and I'd be taking that seriously. Did you have anyone else in the car with you, because corroborating witness accounts change the whole picture.
Also worth noting any physical symptoms after - nosebleeds, unusual bruising, that kind of thing. Not trying to alarm you but those details help rule stuff in or out. Would love to hear more specifics from anyone else who was on that road last night.