Screwfix do a circular saw that has a blade that can cut wood and metal.
It is brilliant for zipping up pallets as it does not matter if you miss a nail or two.
Pro evolution I think is the brand (you could also just get one of the multi blades and fit to another circular saw if you have one already)
trying to cut pallets with a non multi blade is not very successful, the first nail you touch will ruin the blade.