It rather depends on how versatile the tradesman is, Vernon.
You'll need a batten frame within the opening, then plasterboard (carpenter.)
You would then need it plastered (plasterer.)
Plenty of plasterers and carpenters can do both jobs easily. It depends on how co-operative they are.
Alternatively... a carpenter can fix the framing, and then fix "Masterboard" (or equivalent). This is fireproof, and needs no other finish ... just paint.
https://www.travisperkins.co.uk/Promat-Masterboard-6-0mm-x-1220mm-x-2440mm/p/559000
A decent handyman could do whichever you go for.