Banking and finance
We sometimes use cash points to take money from our existing UK accounts. Note that in addition to the exchange rate you get charged 2.5% typically for withdrawing money in Euros, and if you are using a Spanish bank's ATM you get an ATM fee of 2% on top. That's £4.50 worth of charges on every £100 you withdraw.
If you are with a UK bank and that UK bank has branches in Spain, then you can withdraw from the ATM without the ATM fee (so saving £2 on every £100). If you are with a Spanish bank there are account charges for all sorts of things - like statements, money transfers, and you pay a ATM fee if you do not use your own banks ATM - there is no free network in Spain.
If you pay by card in the shops (you will need your passport or Residents card as shops require ID when paying by credit card) then there is no fee, just the 2.5% commission.
If you have telephone banking in the UK you may be able to arrange larger transfers over the phone. It seems it is not possible to transfer money online (we don't know of any UK banks that offer an online international money transfer service).
The Spanish use direct debit mandates all the time and they are compulsory for things like electricity, water and telephone bills, so you do need to have the money in your account. In addition schools take money for school diners, trips, after school clubs by direct debit too.
It can be a little confusing at first but every account has an IBAN number which in full is 20 digits with the first 4 being the country and bank code eg ES12 then the bank code, the branch code, 2 check digits and then the account code. Eg:
ES12 0123 4567 89 12345678
For direct debits you typically only need the last 16 digits.