Can anyone help me with advice on what to do?
A Bathroom wall was plastered and then painted, but the paint has started to crack / flake and fall off.
Do you know how to get all the paint off and should there have been something put onto the plaster before it was painted?
Have you started your bathroom yet?
The plaster needs to be sealed with a primer (any local Hardware store) getting the old paint off should be pretty easy but will take time. Scraping will be the cheapest and probably cleanest way, you may need a little plaster to fill any misshaps.
I read your post and thought you should know about a very high probability that their could be a lead hazard with you bathroom paint. Their are materials available to make such paint removal safer for the do it you selfer. I figure your in an older home "plaster", "peeling" paint. but if you house was built later then the 1970s, I wouldn't worry too much. If it is built in or before the early 70's I would recommend using a lead test kit (can be purchased at most hardware stores) on the paint so you can be aware of the possible danger before getting to far into it.