Hmm. I dont suppose they can refuse a claim when you spend the night away from home, but I wouldnt like to put it to the test if the crime report (theft of or from car for instance) indicates the car was at or near your home address but not garaged as declared. (or parked on the road ,not on the driveway as declared.)
Its quite noticeable how many domestic garages in the UK are never used for the car. Many are too small, have poor access, or used for storage etc. But how many of those owners claim their car is garaged. The difference in risk may be small, but most insurers are only too pleased to refuse a claim if they can find a discrepancy.