System by Eric Brown

Stranded on a hostile alien world thousands of light years from Earth, Delia Kent has no hope of ever seeing her homeworld again...and little chance of surviving the attentions of the evil locust-like aliens known as the Skelt.
Having escaped from the Skelt and made her way halfway across the planet to meet up with other survivors from Earth, now she and her companions-accompanied by a friendly chimpanzee-like alien and a giant spider-crab-face a death-defying dash across the planet's inimical equator to the valley of Mahkanda...where salvation just might be waiting.