To be a bit technical,
Any corrosion will form because you have a mixture of air and water. Remember that experiment you did in school with a nail, a test tube and some cotton wool? This is the same thing.
So you either have to have the system fully drained and dried and seal, or, fully filled, to stop air/water mixing on the internal rad surfaces.
As for the pipes, well, modern houses are mostly PEX/Poly and if so, i can't see this being an issue. Stagnation will be though.
My advice (i am not a plumber) is to spend £15 on some inhibitor and drain the system you have as best you can, then fill it up inc, inhibitor and try to remove as much air out of it as you can and this should be fine until you get a new boiler.
Whilst you have the system down, fit some trv's in the conservatory and put them on frost setting. This will protect your conservatory and the piping.