Thank you so much for all the good wishes, they are very much appreciated

They didn't ring overnight which is a good thing, when I saw the specialist yesterday he said that I would get an update Saturday afternoon and other than that they would only ring if there was any change in his condition. You can't ring in during the weekend as the phone line is for emergencies only but having seen the facilities and spoken to the vet I'm confident he's in good hands.
The vet suggested waiting until Monday for the MRI, priority over the weekend is to get his seizures under control. The anti-seizure medication will make him drowsy/sedated which is a good thing while he's hospitalised so that will help stop him feeling frightened as he will be a bit 'out of it'.
This has just come as so much of a shock as he really was the biggest, healthiest lump - no inkling of anything wrong beforehand

His appetite has been fine, he'd been alert, active and very affectionate still.