Hi Andy,
The biggest worry for a young family when moving to Spain is Employment.
It is far from easy to gain regular well paid employment unless you have a proffesion that is in high demand.
I cannot comment too much on the CDS because i am on the CB but here the main employment is sales,tourism,building and the service industry.
I have a friend who wanted to be a HGV driver and most companies do require a good level of Spanish for delivering within the country,the best bet is to try someone like Union Jack who regulary run back to the uk,they are a removals company,you then have to decide whether or not you want to spend that amount of time away from your family.
It really is the only fly in the ointment when it come to moving here,it is a fantastic lifestyle but is doesn't come for free.
I wish you all the best.
Regards
Georgia