First thing to establish is if it is inside or outside the camera. When you can’t see clearly with the camera, can you simply wipe that off with a soft cloth, and correct the issue, at least temporarily? If it’s mounted high, put a cloth on a stick, to make life easier. If you can’t, then it must be on the inside, and you’ll need to ensure it is well sealed, as described above, but first, you need to make sure you are sealing it dry. You’ll need to bring it inside, and let it thoroughly dry, and then put the back on tightly, before taking it back outside and remounting it.
If you can wipe it off, then it is condensation forming on the outside, maybe your particular mounting circumstances, and the almost permanently damp weather in the UK are contributing. I’m in the UK and haven’t suffered this issue, but maybe how and where they are mounted changes things.
Then again, I have one over a river, damper than could be imagined, and having just left there tonight, a few hours ago, I can confirm it was a little misty at the time, yet the image is still clear, as we speak, and with a current temperature of 6C. Just the right sort of temperature for fogging up.
Others have reported products like rainx or similar, can help if it is on the outside.
EDIT: By the way, the noise you can hear on the audio is the river, some 15 feet below.