hi
you will have to get telefonica to install your line / internet first before you can transfer to BT...at the moment we only have our phone line with BT as telefonica have not yet released the internet line , so BT cannot, at this time take it over. Your best bet is to contact telefonica asap...they normally have someone who speaks english if your spanish is not that good.... we were very luckly...our spanish neighbour helped us out :)
Nothing is ever that straight forward out here...but at the moment the weather is fabulous...so can't really complain that much !!