Here is a pamphlet on Brexit preparedness, prepared by the British Embassy in Stockholm. Now that we have an actual course to follow, the information is quite definitive.
The long and short of it is nothing changes in 2020. EU law will persist and nobody’s rights will be affected.
Things may change after 31 December 2020, but the details of that are yet to be worked out. When there is more to say on that the Embassy will let us know. In the meantime, this covers the essentials.