Children, spouses and life partners of EU Passport holders are allowed to apply for the EEA (European Economic Area) Family Permit in order to join their family member/s in any of the EU countries including the UK.
This EEA Family Permit will grant the applicant entry into any one of the EU countries for a period of 6 months in which time the EEA applicant will have to apply for their residence permit. This Residence permit will be valid for 5 years and will allow the holder to live and work freely in the UK, without any restrictions. After 4 of the 5 years, the residence permit holder will be able to apply for permanent residency or Indefinite Leave to Remain (ILR) for one final year. On completion of this final year, they may be eligible to apply for their British Citizenship and passport. The applicant will still have to satisfy certain criteria in order to receive their British Citizenship.
The EEA Family Permit can be applied for outside of the UK whether the EU passport holder is already in the UK or will be travelling with the applicant. Again, it is important that the applicant provide evidence that they have accommodation and financial support in the UK before they apply for the permit.