I think if you lift the plastic sill covers at the base of the door aperture ( just pull upwards and they will pop off.-you can access the carpet clips. You might have to remove the seat squab pivots/brackets also not sure
They're not easy to get at on the estate. Remove the kick plates as Grober says and you may be able to get a hand in there. The pump is encased in thick foam and is below a small hump in the carpet on the nearside
I can't remember ever removing the whole carpet but, if you need to do it, you'll have to unbolt the belt stalks because they bolt down through the carpet. You also need to remove the black trims round the base of the rear seat pins - they have a hook so push them down, pull them away and they'll pop off
- remove the "kick plate" trim
- pull away the door seal enough for access
- take off the rear seat base
- remove the rear seat belt buckle fastenings
- remove the plastic trim around the "seat hinge"
- pull carpet up carefully
this will provide enough access hopefully.
If not you need to remove the other side of the seat, along with the seat belt buckle fastenings and then peel the whole of the carpet up.