@Wonderingwhyme
If the ridge tiles have actually blown off (and were not already cracked) it must have been extreme wind, they are actually rather heavy. One ridge tile does not make others fall of, they do not rest on each other.
Depending on age of house there may be felt or beathable membrane under the tiles, or nothing. If it is an old slate roof, probably nothing. If it has been retiled with modern orange tiles, probably felt. If it was new build or retiled in the last ten years or so, probably brewathable membrane, which is better. You would have to stick your head into the loft to see, probably with a totch, but if you can see daylight, the roof will leak.
If you think the roof is shedding tiles, wait until rain and wind have stopped. A pair of binoculars is very handy for looking at a roof, or a camera if you have a zoom or telephoto lens.
Roofers will be busy for the next few weeks. When they're not working they will be looking at Yacht catalogues.