How do I see UK motorway junction numbers on Apple Maps?

Apple Maps will show the route badge on a main motorway or a short distance from of a large roundabout, or in the absence of a route badge, you may see the name of the road in all capitals superimposed on the road. In some cases, you will see the large capital road name and the boxed route number badge a short distance apart.

I say that because I am currently looking at a large complicated roundabout in Telford Shrops (which I have navigated in the distant past). Five roads are converging on that roundabout. Only one has a route badge and the others have a capital road name.

Your daughter should have been able to enter her current location in Apple Maps and the destination address and Apple Maps would have provided turn-by-turn, spoken directions to that desired destination. The role of Find My is to locate a device, not its GPS coordinates or routing information. There is a ⓘ symbol on a located device and when you click that, one of the options is directions. I haven't tested this.