I remember similar journeys.
The London department stores made a big thing of 'going to see Father Christmas'. It usually involved a trip in a rocket or submarine (it must have been real, you could feel it moving, and see the passing scenery through the window) before you arrived at the Grotto had got your present.
I must have been taken there in half term, and I can remember being offered the chance of going to see another Father Christmas (this didn't confuse me, I knew they weren't the 'real' one but I enjoyed the show) if I traded my unwanted present, which could be given to one of the cousins on my mothers long christmas present list.