Hi thanks for your reply. I thought it might be a cache issue but I don’t have any cache plugin installed. I’m not sure about the server, but I wouldn’t have thought so.
I have worked out a way around now for anyone that has a similar issue…
I have added <?php woocommerce_empty_cart(); ?> to the ‘Thank you’ page template that woocommerce takes you back to after payment. A little bit hacky but seems to do the job.