Gymbal

Need a bit of help with this one....
Wife and I have flexible mortgage (current account type). I suggested we use credit cards to pay all household bills food, purchases etc. Then pay off by dd full monthly balance of ccat end of interest free period.

I think we are saving one months interest on the food etc say £1000 at 5% (mortage) divided by 12?

But do we save this amount every month or just the first month we do it?

My head hurts.......