Moving to Sweden (S1 form leading to EHIC)

Hello,
I am a British national who recently moved to Sweden to live with my girlfriend. I have just received my S1 form from England but I am unable to find out through the Swedish authorities to whom I should send this form. As I understand it, the Swedish authorities will then process this information and send it back to England in order for the British government to acknowledge my presence in Sweden and allow me to ask for an application form for my European Health Insurance Card. Numerous telephone calls to England suggest that this is the way to get an EHIC. However, telephone calls to Försäkringskassan (the Swedish Social Insurance Agency) indicate that nobody seems to know either what an S1 form is or what to do with it. Can anyone please help me with this matter and tell me where do I send this elusive form?
Thanks in advance!
PS. I am currently looking for work and am also in the process of acquiring my personnummer (personal number). This should allow me to get healthcare benefits as if I was a Swedish citizen, but until then and whilst learning Swedish, my only chance of getting healthcare is via the acquisition of the EHIC.