Cant thank you all enough for the encouragement, its all very much appreciated.
So I got the basic colour scheme sorted, and after looking at tarnished lead, and a quick read up it seems it weathers leaving a white oxide on it, so a touch of grey oil wash, then just some greyish white pastel powders dabbed on it, fixed with iso, so here how the basics look,.
Now its time to get the basics done on the inside, then I can flat coat it and start to beat it up a tad and get it weathered in, and try and get it all to blend together.
The exposed brick work needs to be broke up a bit, but will get to that when the weathering starts.
Thanks for reading.
Ray