I have Telstra Clear cables from the box at the street to:
the front of the house and into the front room;
the room at the back of the garage in the middle of the section, and;
our office at the back of the section.
The distance between the front room where I want to use a laptop, and the office where the present cable modem and wireless router are installed is about 35 metres.
The wireless signal from the router (NetComm 802.11n) will not extend to the house, probably because the office has metal cladding and I suspect is acting like a Faraday Cage.
The simplest proposition is to install a second cable modem in the front room of the house and to connect the laptop to this directly. The quoted cost is $60 which seems a cheap alternative to wireless repeaters.