Renovation of 70s house - replace upstairs partition walls?

alejandro1977

I'm looking at a late 70s house (Semi-D; not falling apart, looks decent from the outside) - the walls upstairs feel like cardboard  - noise travels - is there any way to improve this by adding plasterboard. Someone mentioned removing them (makes rewiring easier ) and adding modern stud walls but it all seems a bit extreme.  
If I were to do this what's an approx cost for a 4 bed semi/145sq m?
I thought I could get  away with drylining and cosmetic updates but everything seems to be "if you do X, you might as well do Y; if you do Y you might as well do Z" - where does it end?

Or are there some jobs that can reasonably wait  without adding excessively to the overall cost? or do I just bite the bullet and  to a complete refurb (after I sell a kidney)?

jmBuildExt

Where does it end?...depends on the budget

Be careful before you go ripping down internal stud walls upstairs.
They may well be supporting stud walls. Didn't think such a thing existed myself until i had an engineer in my house of similar vintage.
He showed me where the roof trusse's/rafter's load was transferred onto these particular studs and below that on ground floor below was supporting block wall.