Following last nights frustrations I did a bit of googling and found these solutions
1) remove mods and complete repair
2) remove fxo and metashaders folders
3) remove dcs entries in appdata file
4) replace mods and launch game, once game has loaded ,load map you are going to play in mission editor, once loaded close then go to multiplayer
This has got me down to about 6 mins from launching game to sucessfully loaded cockpit and ready to go. Previously it either crashed or took 20 odd mins.
Hope this helps others, I will test later for repeatability