Firstly, congrats for the forthcoming bundle of joy !
Though there r ways to get the x-ray done [aka protective shield], during pregnancy, but it should be avoided. And at 8 months, no DMP would touch the lady for that.
Your best option now, is to return the med forms, alongwith a letter to CHC, explaining the situation & asking for a reschedule. The CHC'd agree and most likely, would ask u to notify them asap after the child birth.
Whereafter, obtain a new pp for the baby and send it to CHC. Then, it shouldn't take more than a month to get the new forms & to complete all the formalities.
This is my personal opinion, I might be wrong. So, kindly wait for some more responses before taking a conclusive decision.
Regards,
Qorax.