The EPO has published the "Unitary Patent Guide. Obtaining, maintaining and managing Unitary Patents". The document tells how to obtain a unitary patent, e.g., how to apply for unitary effect and what the requirements are. The document also discusses a number of other topics that are relevant for unitary patent proprietors, including the compensation scheme for translations costs and the registering of transfers or licenses.
The document can be downloaded at the EPO. The document looks nice, is well written and seems to be truly useful. Unfortunately, it will only be really useful once the difficulties surrounding the entry into force have been resolved (see New delay for unitary patent).
Photo by Klimkin from Pixabay under a CC0 license (no changes made).