I've made a few helper scripts for doing EPS test stuff.
Most frequently useful is the NHS number generator, but I also have scripts in here for building and sending PSU update bodies based on a PfP response for a patient. More will be added as I need it.
This has an example of creating and signing a prescription with the FHIR facade in dev: here - implement it. It only works in dev though, since it relies on signing using a certificate, and higher environments require use of a smartcard