You must comply with the SRA Authorisation Rules whenever you practise as a solicitor. These deal with registration and insurance requirements. In short, you should not act personally outside Keystone for others, even for friends and family and if without charge. Instead, your friends and family should engage you (so long as you are independent and note that you cannot act for yourself/spouse/controlled entity) a colleague, or another firm instead. Our duties to friends and family are the same as our duties to all other clients and we can take no short cuts. On the contrary, the file will need to be immaculate to make it clear that none have been taken.
You can administer oaths outside Keystone for anyone (including friends and family). You do not need insurance for this or to register separately as a sole practice with the SRA, so long as your charge only the statutory fee (£5 per document and £2 per exhibit) or make no charge for doing so. You can find out more about this here.