My design has been copied by a foreign manufacturer but I can’t afford to take action in China and would not know where to start?

This could prove costly and expensive so a potential course of action would be to limit their import instead, for instance by enforcing your rights against a UK importer or online marketplace selling into the UK.  Due diligence in checking exhibitions for potential copies is an effective way of identifying these and taking action. Seek legal advice for the best course of action for you.