If you arrive by bus, or park in the main visitor car park, you’ll probably come into Science City past the Science Library.
(Its official name is the George Green library.)
From this perspective, the route you’re going to take runs in front of the library.
The next photo is of that path which runs in front of the library. Compared to the previous one, you’re now facing more to the left (north-east).
Another view from part-way down. The building which you can see a corner of on the right, with the vertical ridges, is the Science Library.
To reach the step-free path to the lower level, turn right in front of the library. A ramp leads down from the far corner of that level, adjacent to the steps near the library. It’s not obvious from a distance.
The ramp does a zig-zag so the gradient is fairly shallow.
Then there’s a single ramp from that level down to the level of the ESLC, parallel to the equivalent steps.
As you come down the ramp, the front of the ESLC is not much further on, on the right.