As far as I know, the springs come out through the cockpit, and I suspect the seats will have to come out, so I wouldn't let a local grease monkey loose on it. It's not a mechanically challenging job but it's quite a fiddle due to lack of access.
My leaf spring competence goes way back to 1971 when I broke my first spring on an MG Midget the day after I bought it. Since then I've changed dozens on MG's but so far, not on a Morgan!