What picture does the poem create of the people here?

There aren't so many people in the poem. Those we do see are referred to in passing: the poem is a sweeping observation, taking in many sights, almost as a bird flies or as a train goes. People appear almost incidentally, as if glimpsed from this train. Notice that the 'workmen at dawn' are shielded (hidden); the 'headscarfed wives' do not show us their faces; the 'cut-price crowd' are just that - a faceless mob.

Larkin also refrains from passing direct comment on these people. All we know of the 'residents of raw estates', for example, is their consumer habits, images which are developed in some detail. Perhaps Larkin is suggesting by placing this emphasis that this is all they infact are, how they choose to be and should be defined.

Nevertheless 'Here' is a picture of the land more than of the people.

Is this a ‘pastoral’ (dealing with an idealised/romanticised rustic or countryside life)?

The poem does deal with country life. It is hard not to read the following without a certain sense of romance being invoked:

Of skies and scarecrows, haystacks, hares and pheasants,
And the widening river’s slow presence,
The piled gold clouds, the shining gull-marked mud

However it is also a portrait of an unnamed city, and you probably cannot have a 'city pastoral' (perhaps it is a cityscape):'

Gathers to the surprise of a large town:
Here domes and statues, spires and cranes cluster
Beside grain-scattered streets, barge-crowded water.

This too is a picture, but it is now a picture of human ingenuity, at work within nature. It is peaceful, and significantly, unpeopled. We might conclude that Larkin doesn't like people very much: when they intrude on the picture we get them as consumers, and only really as consumers. It is left up to us to judge whether they pollute the image or not.

After this interruption the poem returns to its rural theme, sweeping from the city and out to, 'isolate villages, where removed lives / lonliness clarifies.' More images gather, almost avoiding people. And the sweep ends only at the sea where we find 'unfenced existence: / Facing the sun, untalkative, out of reach'. These last two lines are tricky, but they could be viewed as a release finally, from the pressure of observation and of 'fenced existence'; and of release from obligation into silence and, finally the lonliness the poet seeks.