do I need any special kind of solder or will any cheap solder do. I've heard about rosin being used as an ingrediant in solder, do I really need this in the alloy mix?
Andrew, I always use "flux-core" solder for electrical work and non fluxed solder for plumbing joints.
Flux-core solder already has the flux
(which is needed to reduce oxidisation and help produce a much better joint) contained within the solder itself.
Most flux-core solders contain a rosin based flux, making them much more suitable for electrical work than the acid based fluxes which can cause big problems if the surplus flux is not removed thoroughly.
The alternative is to use a separate flux paste which is applied to the area to be joined prior to using non fluxed solder.
If you buy your solder from an electrical supplier, the chances are it will be flux core solder, but if you buy it from a plumbing supplier, it's more likely to be non fluxed solder.
Hope this helps.
Alan