Don't panic. Check your local news services. In some areas the advice will be to avoid affected hospitals. In others, that would be far too long a journey for safety.
Only use A&E for emergencies. But if it is an emergency you will be seen, and you will be treated. Staff are working very hard to make sure of it. Managers have been pulling together contingency plans. Consultants have been stress testing those plans with everything from "what about the phone and bleep system", to how to still access emergency results.
This is an irresponsible and dangerous attack by fucking scum. But for the true emergencies, we will cope. It is what we do. Just, please....don't take the piss. Because this is seriously stretched.