converting imperial to metric is not hard--provide you have 1 extra tool, and some newer (than 20 years old) measuring cups.

all my measuring cups have both cups and liters (or ml) marked on them--and have had since the early 1970's.

the extra tool? a kitchen scale. my current scale is electronic, (Under $25 at ikea) weighs things in lbs/oz (down to a quarter ounce!) and in kilo's. its good for up to over 3 kilo's. its about the size of saucer, and a set up for tare (so you don't weight the bowl with the flour)

1 liter is close to 1 quart--(as a rough measure) so reading and understanding a recipe isn't hard 250 ml of liquid is about 1 cup. (and the smaller the quanity of liquid required, the less precise one needs to be!
for many recipes, the slight difference between a quart and liter won't matter at all!