You wait until you want to get funding for care through the Continuing Healthcare people. Those frailty scores will become very important particularly when Care Homes, who help do the assessment, scale things very differently because they don't want you to have the funding!
You can be considered severely frail at the time of illness to a much better score later down the line. It is usually assessed every time you enter hospital so hardly worth getting worried about.
Also, whilst you might not feel frail, the assessor will make a judgement about this based on what they observe and if they watch you need support in order to walk or other ailments which might lead you to have a medical need, you will score lower.
All in all, it is nothing to worry about and you will get a better service from your GP if they consider you vulnerable!