Guess what it works!! We can input the location data through the relationship table with Employer as the default (hidden field), as you suggested and just adding occupations (occupations is a menu list: id as value and Description as label) and their locations - locations are check boxes (Check = Yes Unchecked = No) against the occupation.
Also used SQLyog for building the queries (linking Job Details, Employer Details and Locations) and loaded them into record set to display the data.
Just set up multiple inserts and now working on multiple updates.
Thank you for your help Jason - couldn't have got my head around it without you.