Read all I could, and finally decided to make a cut-out tab (rather than the supplied add-on trailing edge tab) after reading all of Selwyn's notes. Trimmed the tab to allow for the required 30 degree up and down movement, then glued in foam strips (with resin) to work as backing for the fibreglass sheet to be layed into each open recess to give it all some strength (See Selwyn's site for a highly detailed description of the process).
Hacking ....
The removed section of the elevator
Filling with foam prior to laying fibreglass sheet in the recess to strengthen
