We are travelling to China in March 2016, UK citizens but in France for the winter.

Hey, Tim. In fact, it is a little bit early for you to apply for L type in December because its valid period usually lasts for three months only. However, according to relevant regulations, people coming to France temporarily need to apply for PRC entry permit beforehand in his own country. So I advise that you apply for it in UK at the end of December. The embassy will retain the passport during the whole process until you pick up your passport. If you can get a suitable appointment, the process only takes four working days.