Thank-you all for your help.

Just posting this pic to show the end result.  

Given my time frame and some technical challenges, I am pleased with the end result.

As said you cant really do anything from the outside "but"

when you first look at doing a repair you should first look at what caused it in the first place and aim the repair towards this.

without a picture of the whole item its hard to be certain but in going for mounting pylon on a rear wing element.

Normally you would have ribs,spars an reinforcement in load areas but on the cheapy stuff they don't bother.

wings flexing and pushing down on the pillars under load an its snapped in the area where there is least flex.

Myself I would drill out the two rivets shown in the pic and use them as your inlet points and inject with worth or john burn two part repair resin using the mixer nozzle in the river hole.

Its fairly thick (think p38) an if you get the quick one it sets in 1.5 minutes so doesn't really flow away it stays where you want it.

hold the wing vertical (trailing edge down) an inject away up to an beyond your rivet holes.

The area of the crack is now solid so no more flex.

refit a couple of rivets an do a cosmetic on the outside with fast epoxy/lacquer whatever your weapon of choice is

Thanks again Hanaldo. 

The hairline crack is just the clear coat so that's fine, but I would be inclined to say that the larger crack is damaged fibres. Considering it is in such a load bearing area, I would want to be doing a structural repair there rather than just cosmetic. 

Hi folks.