agreed she does have rights. They were living together 'as husband and wife' for two years (even if though weren't married). Additionally, the husband has to pay some maintenance for the child.
Also, I'm not certain but I think that some muslim 'contracts' are enforcable in the UK. Nikah may be a type of 'contract' and thus he may owe her something under this (engagements used to be binding contracts under UK law and similar principles may apply here, but I'm not sure).