The 'official' RAF jacket isn't shown in the Aviation Leathercraft catalogue as it isn't available to the general public - you have to contact them directly.
Pop's copies are hopefully better now than they once were - they were getting progressively better every time someone bought one. But some details such as the correct colour were never quite right (you can tell a Pop's copy a mile off due to the pen pocket and epaulettes)......
If you get a jacket from Pop's, get them to use something other than the nasty polyester material they normally use for the lining. I had the lining in another jacket changed when I was in Incirlik some years ago and it made all the difference to the warmth/comfort of the jacket.