External door blanks?

[Alan Ambrose]

I would like a double external door, PH level and modern security which I can cover on the outside with old oak planks similar to the barn-like building it's going to go in.

 

Ideally I would like to buy ready-made double door blanks with good quality insulation and a multi point locking mechanism, so I can just cover the outside surface. I know this is not the way that particular industry generally works.

 

Any leads or ideas?