CADW offer a scheme for Home Educating families.
Full details are available here. Free entry is open to families living in the EU who home educate their children. You apply for a letter of authority using their online form. This then needs to be presented at the site. Proof of identity may be asked for in addition (see website for full details)
Letters of Authority are released within 10 working days of the request
(current as at 30th March 2016)