Thanks for that.
From what I've read already this certificate is NOT necessary, but I can if I wish to request one. It is just to
confirm the status, not to switch to another one. That's why it can't be possible to reset the clock for ILR, see below:
You will not require a work authorisation document in order to take employment in the United Kingdom if you are exempt from this requirement. If you are exempt, you will be able to take employment without restriction. You may, if you wish, apply for a registration certificate confirming that there are no restrictions on your taking employment (see paragraph 21 below which advises you which application form you should use).
If you are applying for a registration certificate confirming that:
• you are self-employed; or
• you are self-sufficient;
• you are a student;
• you are exempt from the requirement to obtain a work authorisation document
because you fall into one of the categories in paragraph 7 above;
you should complete form BR1.
7. You will be exempt from the requirement to obtain authorisation to work in the United Kingdom if:
• you have leave to enter under the Immigration Act 1971 and that leave does not place any restrictions on taking employment in the United Kingdom. For example, you have been given leave to remain as the spouse of a British citizen or as the dependant of a work permit holder;
• you have been working with permission, and without interruption, in the United Kingdom for a period of 12 months ending on or after 31 December 2006. For example, you are already present in the United Kingdom as a work permit holder employment (for example as a student and you have been in part-time employment continuously for 12 months); [...]
Can you imagine if a self-employed person decides to request a certificate confirming his/her status, to reset the clock for IND and add another 5 years of waiting? It's the same for students, self-sufficient people, and those who are exempt from work authorisation, e.i. having Leave to enter or remain, or legally working for at least 12 months in the UK.
That case I think requesting that kind if certificate would only confirm my rights to work legally in the UK, without any restrictions. At least, acording to the current HO forms and guidelines, this is what we should understand.
Fingers crossed I am right!
Thank you all for all your thoughts!