I sent the notification form off in December, and other than a holding letter haven’t heard anything from them since.
At work, I regularly liaise with DVLA over their driver medical standards (see https://www.gov.uk/government/publications/at-a-glance ). For neurological conditions like MS, there is no automatic action - they have quite a bit of discretion based on your symptoms, progression and ability, including leaving you on an unrestricted licence, putting you on to 1-3 yearly renewals, or requiring you only to drive an adapted car. DVLA will write to your doctors and neurologist for their opinions before making any decision, and a driving assessment (which should be very different in style from a driving test) may be arranged if they need to independently assess your capability.
The standards are slightly stricter for professional drivers (holding a ‘group 2’ driving licence - bus, lorry, ambulance drivers, and also taxi/private hire drivers, as many councils mirror the DVLA medical standards for licensing purposes), and drivers experiencing severe progressive/disabling symptoms may be refused group 2 licences in future (although group 1 licences for personal use may still be issued if the applicable criteria are met).