It's very remiss of me not to have made this post earlier. Classic Train and Motor Bus in George Street, Leamington Spa, is my local model shop and a very good one it is too.
You will surmise from the picture that the shop isn't in the high street and you'd be right. In fact like the best model shops it's bit tucked away but well worth the effort to seek out. The walk is short - about 5 minutes tops from the Jephson Gardens in the middle of town where you can leave the family.
Inside, the shop is tiny. And packed with stock. Lots of RTR is available along with loads of kits of all description. Most of the stock is OO and N gauge but odds and sods of other bits turn up occasionally. There is a selection of second hand as well.
The best thing about this shop is the bits. One wall is covered with an ever changing display of kits and bits. There are also several large drawers that just demand digging through to unearth gems.
If you can't find what you want, just ask Mark and he'll be only too happy to order it for you.
More details and a map in this UK Model Shop Directory entry.