how thick is a standard circular saw blade
Yes they do. Any circular saw should have the size right on the saw some where. Standard is 7 1/4  NOT 7 1/2 For wood cutting blades 7 is standard for concrete (Masonry) or metal cutting blades. I guess you are in the UK or somewhere then. The 165 mm is equivalent to a 6 1/2  saw in the states. That would be the standard size for a cordless battery operated circular saw here.