You may have booked a super cheap flight or holiday deal but have you thought about the hidden costs you might pay once you?ve stepped off the plane? Do you know how much it will cost to withdraw cash overseas, for example?

Use the wrong credit or debit card in the wrong ATM to draw cash and there?s a good chance it will cost you a small fortune - as much as ?6 in fees for every ?100 you withdraw in the worst cases. With charges like these it?s no wonder British holidaymakers pay an estimated ?355m each year in hidden fees on credit card cash withdrawals.

But why? Well, first of all, your credit card issuer may charge a ?usage loading? fee of as much as 3% on foreign transactions, perhaps adding 2% to 3% on top of the other charges for cash withdrawals abroad. Even debit card issuers can slap on a fee every time you use an overseas cash machine.

Do your homework, however, and you could cut most, if not all of these charges. Some issuers have low or 0% fees on foreign transactions. Nationwide and the Post Office for example do not impose any foreign exchange loading fee at all, while UK Citibank current account holders don?t pay ATM fees overseas.

It pays to do your research by comparing the different deals out there, says Sophie Neary, product director for Beat That Quote. "By logging onto Beat That Quote you can find a summary of the best credit and debit card deals in a matter of seconds and find out the true cost of using your plastic on holiday."

Foreign transaction fees pale into insignificance, though compared to the medical bills and other liabilities you could face if you fail to take out holiday insurance.

The good news if you?re travelling in Europe is that there is an EU-wide agreement of member nations to treat each other?s citizens in cases of accident or ill-health. Pack your free European Health Insurance Card and you should be assured essential medical treatment.

The bad news is that the standard of cover this provides will vary from country to country, so it is by no means a guarantee you will get the best treatment and you may still have to pay something towards your medical costs.

Outside Europe, even this limited cover is not available, so you should think of arranging a suitable travel insurance policy as being as vital as taking your passport and credit card. Not only will it cover medical expenses, but it will also extend to cover for cancellation, delays, personal possessions and personal liability, a vital thing to have in these litigious times.

Fortunately booking travel insurance online is easier than ever, says Neary. "Don?t even think about risking travelling without the right cover, it?s just not worth it. Beat That Quote can find you the cheapest travel insurance deals in seconds whether it?s single trip or increasingly competitive annual holiday cover you?re after."