I used to live in the UK and my planes were mostly stored in the garage. A squirt of 3in1 oil for the engine and a charge on the batteries before hanging them up in the rafters was all I did. I would cycle my small NIMH in spring before using them.

I think it might be different for lithium batteries, I remember reading somewhere that 40% charge is optimum for storage but I am not up to date on this.