You can bring traveller's cheques or get euros before arriving but the
easiest way is probably just to bring your debit card - they work in all of the
local automatic teller machines.
Almost all business will take credit cards - in particular supermarkets,
restaurants and petrol stations.
The quickest way to Mougins from the airport is along the A8 peage - this has
a toll at Antibes which currently costs 2.40 euros - but you can use a credit
card.