Hi leyshon, you don't need the spanish citizenship, since being english (european) you are entitled to work in every country of europe, but you'll need a degree (either spanish or apply for the recognition of your degree in spain). Apart from that, the most important thing is your fluency in the spanish language, although you only have to prove it in the last part of the proccess (personal interviews). The whole proccess is different from nats. If you are interested have a look here:
http://www.aena.es/csee/Satellite?pa...=1077107881501
And in the best spanish atc web page:
www.limaeco.net/forum
Any doubt, do not hesitate in contact me.