Hi kieran, to do it properly you will have to take off both rear wheels, and then locate the adjusting wheel for the shoes.
On the right hand side it will be at about the 9 - 10 o'clock position, and on the left at about 2 - 3 o'clock, in other words opposite to where the cable enters the backplate.
You will need to slacken them right back.
Next is to remove your rear seat base, or tilt them forward if a coupe.
Under the insulation is a panel with 2 8mm screws and a 13mm nut, take these out and remove the panel, the handbrake cable adjuster is just there. Slacken off the 13mm nut on the cable.
More then likely it will,be partially siezed so give it a good lube while pressing the park brake, hold the release handle at the same time to make it easier.
Once it's nice and free you can readjust the shoes in the discs, then adjust the cable.
Chances are though if you can spray lube on the adjuster from underneath and work it in, it should be ok, certainly enough to take the light out, which is a lot less hassle