Short back story. We currently live in the UK, my husband owns a business which supports us and I'm a SAHM with three preschoolers. We have sufficient equity in our house to buy a considerably better one over there at current prices (nothing fancy but big enough for the family, which this one isn't). My MIL lives in a very ex-pat area on the Spanish coast which isn't my ideal but is nice enough as a stepping stone to living in the country. We're considering the move over there to be closer to her as she's getting older and showing no inclination to move back here, and she misses her grandkids.
We've both discussed moving abroad in a theoretical way over the years as part of 'the dream', I'm happy enough to up sticks and the kids are of an age I feel it would be easy enough to move them/pick up a language. My only real hesitation really is that my parents live here and also dote on our kids and currently see them at least once a week. Travel for them is difficult as my dad isn't in the best of health. However I do have a sibling who lives in the UK (other sibling also abroad) who doesn't live nearby but could be counted on in an emergency.
Really just looking for any and all input and opinions from those with experience of moving/living in Spain. My main practical concerns are financial (tax implications of different income/residential countries) and of course the looming shadow of Brexit. Any helpful links would be wonderful as Google seems to be a minefield of contradictory info! I'm not looking for a bashing on the decision to move, but constructive help would be very gratefully received. Thanks!