You can give as much money as you like away, the potential tax arises when you die. At the moment as long as you survive more than seven years after the gift there's no tax to pay; otherwise there are various exemptions and sliding scales which are what help to keep accountants and lawyers in business ☹️.
HOWEVER there are rumours that Rachel Reeves is planning to drop the seven year moratorium in her autumn statement, so that all lifetime gifts count towards the tax bill, however old. So might be wise to do it before October - and even then, she might backdate, nothing is certain.