From the article, non-citizens of the UK have to pay for medical services, unlike here in the US.
Prayers for the little ones and the parents.
In this specific case, it seems that the medical costs have been covered already:
Russian gives birth to quintuplets, defying doctors - Times Online
All the medical costs have been met by a group of Russian philanthropists. Chief executive of Oxford Radcliffe Hospitals Trevor Campbell Davis said: “We are pleased to be able to give the care and support the family needed.