British wartime contraception consisted mostly of douches or coitus interruptus, as condoms were rare and IUDs (intra-uterine devices) not widely available. The Pill was still only an idea in the laboratory.
Unwanted pregnancies were common, resulting in many backstreet abortions and adoptions.
The practical demands of wartime changed social customs beyond all recognition. People enjoyed far greater social freedom than before, with more opportunities for encounters with members of the opposite sex, and a sense that normal rules did not apply in the face of so much imminent danger. BBC UK History - Women At War
As a consequence of the changing social patterns brought about by the war, sex education became more explicit. Nevertheless, there was a considerable increase in single mothers during the war.