If I just leave it in the workshop until the 29th April, is that it...I can ride it again and just worry about tax and insurance moving forward?
You do not need to get an MOT if:
The vehicle was built or first registered more than 40 years ago.
no ‘substantial changes’ have been made to the vehicle in the last 30 years, for example replacing the chassis, body, axles or engine to change the way the vehicle works