I currently pay 12.5% into my workplace pension but I only work 16 hours a week so it's not a lot. I can't increase it as I need the money most weeks. However now and then I will have extra money or save up some money so I was thinking of opening a SSIP to pay adhoc as I can't do this with workplace pension. Does this sound like a good idea or should I put any spare money in S&S ISA?