Gav,
Does your scanner have a twist-off whip antenna? In that case it's really easy to make a home-made antenna (technically called a dipole) with a lot better reception.
You need a bit of RG-58 wire. This is coaxial wire, normally black, with an impedance of 50 ohms and was used in the not-too-distant past for "thin ethernet", to network computers together. Any IT professional or shop with a sense of nostalgia will have miles of the stuff lying around.
Snip the connector off of one end and either splice the core out of the mantle over a distance of 62 cm (1/4 wavelength of the middle of the frequency band), or use some household electricity wire and a few fasteners to attach a bit of 62 cm wire to both the core and the mantle. Spread these so that both pieces of wire are in line with each other, but obviously not electrically connected, and mount the antenna vertically somewhere high up (mine is in the attic). Avoid metallic components when mounting. Works great.