Hi Mejaz,
If I read you right, you're intending to alternate between the UK and Spain for 6 months each year. Notwithstanding the logistics of such a move (many retired/rich people spend part of the year in Spain) you expect to find work and put your children into the fee paying (expensive) education system - probably an International School - to maintain their British based curriculum. If you put your children into the local education system they will be taught in Spanish, and may struggle if they are there on a part time basis.
Unemployment is very high in Murcia so you may need an exceptional talent. How about a unit in Al Katraz - all day breakfasts, Cruz Campo at €2 a pint all day, premiership footy, kareoke and bingo on Fridays - the only business that will make money!!
Seriously, you need to do your homework on this, I wish you all the luck in the world - many of us just dream about such a move.
keeve