That bolt is known weakness, and if you think it gets a lot of stress over its life.
The to arms are not expensive even if you need one. It's just fitting it, which again isn't that difficult. It's one long bolt at the subframe end, and the to ball joint nut. Not much else.
It's a pity it happened at this time of year as it makes it less pleasant to do.
If the bolt snapped right where it bolts in to the top arm you might not be able to get the broken bit out very easily. It could be a replacement top arm as well.
Hopefully it has snapped with a bit sticking out to get hold of. 🤞
To access the bulb you need to remove the instrument surround front (4 screws), and then repeat the Speedo pod (4 more screws and the wiring connectors). Then you can access the bulbs from the back of the pod.
You could swap a known working bulb and then just plug in the connectors with it all left unscrewed to test.
