Has anyone experienced rattling from their roofs on Peugeots 206cc (04) models, its driving me up the wall!!! Im concerned it will cost a lot to fix :-(.

If it will cost a lot then do not fix it. Squeaking can usually be fixed by a drop of oil in the right place. Rattling may just need a nut tightening. The hard part is finding the right place/right nut so an amenable passenger might help. If you can not fix it yourself you are best leaving it. If you go into a garage and ask them to fix a squeaky roof you are likely to be robbed.

Try feeding the mice.