A significant number of child refugees will arrive in the UK from the migrant camp within days, the BBC understands.
Officials have been focusing first on unaccompanied minors who have the right to join relatives under EU legislation.
A separate registration process will take place for vulnerable children who do not have family in the UK.
Under EU-wide regulation, asylum claims must be made in the first safe country a person reaches, but children can have their claim transferred to another country if they have family members living there.
The Dubs Amendment to the Immigration Act, originally put forward by Labour peer Lord Dubs, also requires the government to arrange for the transfer to the UK and support of unaccompanied refugee children from Europe.
Britain is expected to take more than 300 children in total.