Steve have you considered servicing the car yourself? If you cover over 1000 miles a year you will likely be already familiar with greasing the front suspension which requires this to be done over the period. All that's needed are a jack, axle stands, grease gun plus a few spanners imperial and metric, all of which can be bought for less than cost of one garage service.
Regarding MOT any garage registered to perform class 4 (car and light van) tests will be able to renew. You may need to explain the fly off handbrake and greasy front suspension (unique to trad Morgan's) although excess should be cleaned off.
