EU retired national wanting to move to the UK

Good afternoon, I am a EU retired person of independent means looking to move to the UK to be close to my daughter and her family. Post Brexit I know that the immigration rules have not changed in the UK in terms of freedom of movement for EU Nationals but I would like to know what do I need to do once I am in the UK to prove that I am living there now? I cannot apply for permanent residency not having lived there 5 years and I am retired so will not be working. Any help would be much appreciated.