I Googled
hipg and it took me to the HMRC website. From there, I found this page:
http://www.hmrc.gov.uk/hipg/how-to-claim.htm#6It gives an address:
HM Revenue & Customs Health in Pregnancy Grant
Comben House
Farriers Way
Liverpool
L75 1AX
[…]
Need further help?
You can contact the Health in Pregnancy Grant Office in a number of ways.
You can email a general enquiry by following the link below or you can contact the Health in Pregnancy Grant Helpline. The Helpline is open between 8.00 am and 8.00 pm every day except Christmas Day, Boxing Day and New Year's Day. The numbers you can ring are:
* Tel 0845 366 7885
* Textphone 0845 366 7886 - if you are deaf or have a hearing or speech impairment
If your preferred language is Welsh you can call on:
* Tel 0845 302 1489
IIf you’re calling from overseas you can also contact the Helpline on:
* Tel + 44
292 050 1178
Try this "overseas" Cardiff number, 029 20501178. I suggest you withhold your number using 141 if it isn't withheld automatically.