Hi
hope this helps
i have for the last 10 years have done the same thing
bought some euros when the exchange rate is good now about 1.45 is a good mark
take enough for a couple of days say 70 euros each
depending on how many there are of you
if you have a good secure accomodation including safe
take two -three hundred in notes
depending on how long you are going for
for anything else use your bank card
note for purchases i only pay on my barclaycard
for the insurance cover
a lot depend on what sort of holiday you are going on
if young and going on a bender or in cheaper accomodation dont take a lot of cash .........use yor bank card