read general condition number 6 on the back of your licence
6. the record referred to in condition 5, shall be made in the animal keepers' record book immediatly following each acquisition or disposal. in the case of protected native animals being breed by the licencee, the record is to be completed within seven days of birth or hatching for reptiles or mammals. for birds, the record shall be made within seven days from fledgling. for amphibians, the record shall be made within seven days of resorption of the tadpole's tail.
if you do buy a pregnant female wen the babies hatch just under remarks in the log book or ebook note down that she was pregnant wen you bought her.