egg and chips
I know there are quite a number of N gauge modellers in the county, but most I know have modern image interests so another steam person is most welcome.
My layout will be based on the Gloucester to Bristol which had both LMS & GWR interests and have acquired a lot of info from the Middleton Press publication Gloucester to Bristol. They do publish several books relevant to SDJR in their Country Railway Route series.
On their website there is a list of all the stations covered in their books (all have track diagrams where relevant as far as I know)
Contact me using PM and see if we can set something up in the way of help. I use a design program called RailModeller which is Apple Mac only but it does produce very accurate drawings in a variety of scales including 1:1.