is there any sort of landmark or view out the window of the train to Blackpool from Preston that might have been surprising or unique ?
There certainly was (and still is) -
Blackpool Tower!
In the 1960s, when on family trips to the seaside by train, there was always a keen competition between myself and my younger siblings as to who would be the first to spot Blackpool Tower in the distance as we approached across the Fylde plain.
Being in the late 1960s, we were travelling to Blackpool North. However, in 1950, I suspect most trains from Liverpool to Blackpool may have run into Blackpool Central, which took two possible routes - direct from Kirkham, or via Lytham and the coast. I'm not sure how visible Blackpool Tower would have been from the train on the two routes into B. Central. Potentially the tower would be visible from the direct (Marton) route, I've just never been that way so haven't seen it for myself. Depends how historically accurate you want to be, I guess.
[EDIT] Another landmark I remember from childhood trips to Blackpool (also still there) is a large, prominent white windmill - the
Lytham Windmill. But I think I recall this from journeys by road coach - possibly the windmill is too far from the railway to be very visible from the train, but anyone who has been a passenger on a present-day train to Blackpool South may be able to confirm.
The sight of either Blackpool Tower (from the train) or Lytham Windmill (from the road coach) certainly ramped up the excitement for us kids, as they were sure signs that we were "nearly there".