Most foreign headlights dip vertically downwards so don't need convertors. Most UK headlights dip down and to the LEFT: great in UK to give more light to the kerbside BUT a danger on the continent where light is directed into drivers eyes. And even if they didn't need them, would two wrongs make a right?
Don't drive at night! Also don't drive through any tunnels where you need headlights on; don't suffer any disasters which require you to go to hospital at night; don't allow any nasty virus to arise which might necessitate an overnight drive to a Channel port so that you can return home urgently; ensure that any accident you are involved in is attended by police who don't object to you breaking the law of their country.
All to save £5 on a piece of plastic film!