I like a bit of DIY myself.. Having spent much time watching "how to" guides I'm having a crack myself on something major and it's easy to find out what is needed online because it ain't rocket science is it?
Getting a pro in would probably work out more economical all things considered but finding a good un who turns up when expected and does a good job eh?
The hard bit is actually having the required skill with the tools I reckon which probably comes with much experience..
If this was a job I had to do, i'd tell the missus to be grateful for what she gets, then I would probably fill and scrim the cracks prior to the old pva and skim coat.. Looks easy to me and is the kind of thing I have done in the past without a thought.. Assuming of course it isn't blown, in which case I'd knock it back where needed..
But, the finish wasn't perfect, which I disguised with that old trick, covering it with a paper that had a nice small pattern which hides imperfections better!