Hi
On my disco 3 hazard lights come on there own and central locking opens while driving then it will go back to normal cheers

Well that function is carried by what is known as a “inertia crash sensor” and is part of the security system. It will operate when a vehicle receives serious bump as in a crash or even a significant pot hole, then switching the hazards on and unlocking central locked doors, if locked.

The sensor activation requires a manual reset, so as yours doesn’t suggests your vehicles system has a fault, perhaps a simple wiring issue, perhaps its gone over sensitive as inertia sensor can, if so then repair is by replacement of the whole module not individual components.

So if possible have a diagnostic test on the system.

Have a diagnostic run.
How old is the battery?
How tight are the battery connections?
Is the alternator outputting the correct voltage?
Going by your symptoms the battery voltage is likely dropping below 8 Volts.
If this happens, the JCB (body control computer), enters CRASH MODE, which pops the door locks, puts the hazard lights on, and illuminates the interior lights. It may also prevent the engine from running, unless the ignition is cycled a couple of times.

A diagnostic read will confirm if crash status has been activated.