I woudl really like some pointers/help about returning back to the UK.

I left the UK at 15 and have lived in South Africa ever since - therefore have never worked in the UK.

My siblings have moved to other continents , my parents and grandparents have passed away so there is nothing holding me here anymore and would love to move "home".

I have a current passport and have been back a few times but have no idea where to start in terms of tax numbers, national health, banking, resident card ( only heard about this one recently- do i need one?)

I have some cash and a place to stay for a month either near Leeds or Winchester. Has anyone recently returned and started from scratch in terms of documentation ? Or can anyone point me at a website where I could get information. I'm told by ex-work colleagues who are in the UK that with my banking skills I should find a job easily but am I entitled to any unemployment or other benefits?
Thanks everyone in advance.