Robs931

Hi everyone, So my timber frame build at the moment has been designed with an arched soldier course above every opening. This currently is to be formed with a straight steel lintel and a preformed uPVC arch former sat on top, but I am now unsure how this will look once the windows are installed. This is due to the fact that I believe the windows will be set back in the brickwork around 50mm and as far as I can see in pictures online the uPVC arch former is only set back maybe 20-25mm from the face of the brickwork. I'm unsure how this possible 25-30mm step will look between the window frame and the lintel/arch former. Does anyone have any pictures of their windows with uPVC arch formers which might give me a better idea? My other option would be to use timber arch formers and remove them after the brickwork has cured leaving a self supporting arch and then fit a filler piece above the window to fill the arch. This would at least mean that the arch filler is recessed in to the brickwork the same 50mm as the window frame and in my head look better/neater. But my building regs drawings state the use of a steel lintel with uPVC arch former, if I then changed to timber formers would this be an issue with building regs? Would I need to resubmit updated drawings or anything or is the BCO not likely to even notice the change?