I have used the following crowd in the past here in Cork for two cars I used to own.
http://www.solargardireland.com/vehicles.php.html
When asked how much I could go for he said I could go as dark as I wish at the back while at the front, as mentioned on their site:
Main Changes to the NCT - From April 1st 2010
"The glass in the windscreen and front side windows will be required to have a light transmission level of not less than 65% in order to pass the test"
This basically means you are still free to tint your windows as dark as you like up to the drivers door. It is only the front driver and passenger door windows that are subject to NCT Regulations. It appears to be at the discreation of each NCT Centre whether the light tints are accepatable or not.
So if I were you I would do the rear 7 windows like Tony and leave the front 3 clear or have a very light tint in order not to fail NCT?