hi there,
method statements- are for activities, ie floor mopping, floor vacuuming, dry wiping.
risk assessments- are for the job being done, and should be site specific. we have a risk assessements for a new build house cleaner, and then bolted onto that are a number of other risk assessements, these include, portable power tools/appliances, traffic managment, slip, trips and falls, and manual handling.
coshh assessments- are an assessment of potential dangers when using or carrying out a process with a chemical, and by processess, that includes storaqe, transportation and decanting of the chemicals.
hope that helps a little
regards
martin