In my experience owning a classic is like marrying a crazy but very beautiful girl.
Anyway the car I think you are referring to is either an MG MGB or an MGC, the MG 18 stopped production in the 30's from what I recall. As much as its still not considered a true classic, its a great car and will sure turn heads when you take it for a spin on a nice sunday afternoon.
Well spares are definitely an issue locally, but you can get any part from UK and there are custom spare part makers if worst comes to worst. Plus the cost of MG spares compared to other classics is cheap.
Before you can be be old and wise, you must first be young and stupid.