The rail bookshop situation in the North West England is to put it politely a bit sparse.
The Carnforth bookshop I agree about their stock,even those for internet...In short not worth a trip.
I presume you are talking of secondhand,so here are few to try,with comments.
KWVR...Haworth has a large range of new rail books,inc Lightmoor etc..Also some new overstocks reduced prices and some S/H....Ingrow is a rail magazine back issue heaven,if you are into them...But prices are not job lot pricing...Certainly good for rail modeller and the rail socities mags....Book side is all S/H and varies between the £! section ,think of Mr Adley to a large selection of rail books,quality and prices vary...Not the cheapest.
Embsay till about 5/6 years ago had a rail bookshop open throughout year,but finally packed in due economic reasons...Still stocks new rail books,but on a more limited scale also has a s/h section as well.
Nick Tozer,see his website as his opening hours are bit quirky.
Best Rail b/shop in Manchester area moved about 4 years ago...That was Martin Bott at Horwich,he moved 300 miles to Felixstowe!!...If you are down that way,would recommend a visit.
My knowledge is otherwise limited,as most heritage rail lines seem to avoid this area of income generation.
Two well outside area ,I will recomend and thats the Nene Valley railway at Wansford,the TPO coach,a great place to rummage and The Emporium at Loughborough on Great Central...They get bequests of 3.0k books!
Most other lines I know of ,the Wensleydale @Leyburn and Leeming Bar,Eden Valley Railway at Appleby have very limited stock so as to make a visit near useless
The mention of Charity shops,I find amusing..Very few get rail books given to them and frankly when they have them pricing is all over the place...The only one that markets rail books,in shop and on line is Oxfam ,and god they can be grossly overpriced.!
East Lancs try the Standard tank bookshop...Since fella left last Dec,the 2 ladies have been like a breath of fresh air and when I last visited,stock had been culled where there had been 10 of same title ,now there was 2...Mags were also set up to sell,not stock.
Finally as a part time bookseller,is the attitude its a railway book,it will sell whatever....Condition is paramount to me,and also,oh its another pre 2000 IA or something similar