Renting long term in spain

Hi

I retire July next year and we would like to spend a year or so in Spain, we would be looking for a two bedroom Finca or similar preferable with pool.

Question: what is the best way to go about finding one, can we do it from here (Kent) should we come over in advance (how long) there are opportunities on the internet but do you have estate agents like England?

Also what is the current feeling over Brexit? all we get from the media here is conflicting crap.

Regards

Phil