Insulating a brick cavity wall

[Haden]

Hello can anyone please help? I have decided to insulate the exterior wall of my living room. Trying to use my common sense I've decided not to use cavity wall insulation as I don't wish to run the risk of future damp issues. I'm opting for kingspan K17 on the inside. I have a square bay type window and I've removed the surrounding woodwork. Where the brickwork ends and the window starts I can see the cavity between the interior and exterior brickwork, this gap was covered by a thin facia of glossed wood and I was wondering if I could put some sort of insulation foam strip (aprox 2"x2") before putting a new wooden facia over it or would I still run damp risks even though it's not exposed to the elements?
Sorry it's such a waffle

[welsh brickie]

I personally would use fiberglass in that situation and really cram it in its water resistant.