We have heavy curtains and have put up the poles using the usual rawl/wall plugs and screws- sadly no battens to drill into! BUT the pole fittings are pulling out of the walls, rawl plugs'n'all! What we need are those things you feed through the drilled hole that you then 'unscrew' to pull the backing 'plate' up flush against the inside of the plasterboard so it can't pull out! You then screw your screw into them.
What are they called as I'm sure the 16 year old I ask at B&Q won't have a clue!