You can simply bring your Sterling cash with you. You will probably want some to spend on the journey anyway (for example at the UK departure airport). However, you will need to change it into Euros when you get there. You can do this at most hotels, airports, exchange bureaus (casas de cambio), travel agents and banks. There will be a charge levied either in the form of a commission, an unfavourable exchange rate, or both. A bank will probably give you a better deal than your hotel. However your hotel is more convenient and the hotel reception will be open longer hours than the bank. Banking hours in Spain are usually 8:30 am to 2pm.
It is worth having at least some of your cash in local currency before you travel. Then you will be able to buy a drink, meal, etc as soon as you arrive without having to worry about cashing a traveller's cheque or changing your money. You can buy foreign currency at banks, exchange bureaus, travel agents, and the post office. You will pay to do this by a commission, an unfavourable exchange rate, or both. Shop around! You dont have to use your own bank so try telephoning all the high street banks in your area to get the best deal. Internet and telephone banking services may also offer a good deal. For example if you have an account with the telephone/internet bank First Direct you can order your foreign currency by phone and it will be sent to you by registered mail. The Post Office can offerforeign exchange free of any commission but the rates are usually slightly worse than those offered elsewhere. Call into any main Post Office for details or telephone 0845 7223344.
Bringing your debit card or credit card on Holiday is a good idea. Even if you don't use it its nice to have for emergency use. You can use your card to pay for goods and services in many shops and restaurants in Spain. In addition you can get cash from most cash machines in Spain. Using your credit card or debit card abroad will incur charges and may not attract the most favourable exchange rates and/or commission. A phone call to your bank or card provider before you go will warn you of these and enable you to choose the cheapest method. Ask the following questions:
Travellers cheques are a safe way to bring money on holiday but not the most convenient or the cheapest. You will need to buy them from a bank or agent before you travel and you will need to exchange them for foreign currency when you get to your destination. You pay commission when you buy travellers cheques and some outlets also charge a fee when you use them on holiday. The inconvenience and charges are balanced by the safety. If you lose your travellers cheques, or if they are stollen, you can claim your money back. Useful in particular if you intend taking a large amount of money on holiday.
You may decide that the cheapest method is not the easiest and you may be prepared to pay a small premium for convenience. Remember that when you are changing money it is usually more cost effective to change a large amount at one time rather than several small amounts on different days. If you are travelling as a group it may save commission if everyone changes their money as one transaction. Remember to organise your money well in advance of your holiday, travel agents and small bank branches can take several days or longer to order your foreign cash.