I survived the transition to decimal with the help of a couple of mnemonics. Five and ten and twenty-one, winter, spring, and summer sun (and 30 is a heat wave) A litre of water's a pint and three-quarters.
I use either one or the other, depending on the context. Baking cakes is still by imperial measures, as most of my well-tried recipes start with 8 oz flour. I have acceptedat last that a tablespoon is 15 mls and a teaspoon 5 mils. However, baking bread with my Panasonic breadmaker (bless it) is in metric, because that is how their recipes are. Thank goodness my scales can switch from one to the other.
My height and weight are imperial, my shoe size is metric, my clothes are some of each. New babies are born imperial, whatever they become at school later. Miles travelled are imperial, but fabric is bought by the metre, though its width is in peculiar numbers of centimeters, which must reflect the width in inches.