I have brought the s7 and s8 from stream for the met route but there is an advance version of s8 and I think s7, does it come with the normal train or do I need to buy the trains again from just trains website?
The version you bought off Steam is the same as the one on the Just Trains Website If you look at the manual for the train in \railworks\Manuals you will see it says S8 Advanced. https://store.steampowered.com/app/1147157/Train_Simulator_London_Underground_S8_EMU_AddOn/