The British law have specified in the Nationality Act which was enacted in the late 90s that anyone who wants to apply to become a British citizen must show amongst a host of many other things that such a person is not subject to immigration restrictions in the UK. What this means in the simplest of terms is that, such an individual does not need a visa to be in the UK.
This means that you cannot switch from a visa to becoming a British citizen. You would first need to have obtained a permanent residence status or an indefinite leave to remain before you apply for a British passport. Regardless of how long you have stayed in the UK either on a visa category or as an EEA national, you have to have obtained an indefinite leave to remain or a permanent residence status before you can apply for a British passport.
Most importantly, you need to have been free from immigration control (have had indefinite leave to remain or permanent residence) for a least one year before you can apply to Naturalise in the UK.
Nationals of the European Union and European Economic Area and their family members were until 12 November 2015 in a position to qualify for Nationality or a British Passport once they have resided in the United Kingdome for a continuous period of five years, had continuous residence throughout the previous 12 months of that period and met all the other requirements.
Change to rules
November 12, 2015 marked the introduction of a very important rule in applying for British citizenship. The government of the United Kingdom introduced a new rule that says that a person would need to first apply for permanent residence certificate referred to many as the Permanent residence card before they can apply to naturalise or apply for a British passport. This new rule can be found in the British Nationality Regulation (2010) Amendment number three. The appropriate sections have also been updated in the Home Office’ guidance which can be found in pages 19 and 22 of the same Home Office’ guidance on Nationality.
There has been a general but rather erroneous belief that you need to have been issued a permanent residence card before you apply for your naturalization. Please note that this is not entirely true. The law says that you must have had permanent residence for a period not less than twelve months and have possessed a permanent residence card.
Recall that I said that you acquire permanent residence after 5 years of continuous residence in the UK (while exercising your treaty rights – working, studying or self-employed) regardless of whether or not you have gotten the card. This means that even though as an European national you are not in possession of the documentary evidence to show that you have permanent residence, you have in the real sense of the word already acquired it by the reason of your exercise of treaty rights in the UK.
What this means that if you have lived in the UK for a period of at least 5 years and exercising your treaty rights, you can apply for Naturalisation immediately after you apply for and obtain permanent residence.
For more info, visit here: http://reissedwards.co.uk/