Been several years since I was last at that particular piece of track but it certainly used to be possible it get there. There's a slip road near the bridge which allows vehicle access to the track, I think the No Entry sign refers to that. From memory there's a smallish gap next to that which leads to a grass bank.
There's not much of a fence so you can get a reasonable
side-on view or a bit further round going into
Hawthorns. As I said it's some years ago so things could have changed since then.