Ex-pat with property in the Uk looking for pension and business entity formation

I’m an expat living in the USA and have 3 rental properties in Cheshire  and looking for advise on returning to the Uk and managing these as a business instead of currently just buy to let mortgages as a sole entity

I’m looking to setup a pension and also re contribute to my national insurance for any missed years

Would you have any suggestions articles or an FA and tax person you would advise me talking to for planning.

All input valuable thanks