Visa appointments for visa type R/ class B1/B2

Hi, I applied for visa renewal at the beginning of December 2020. If you are over 80 years old, or nothing has changed since the original visa application, then they say you may not need to go for an interview but I cannot find any help for this.
Also, will I actually need a visa now just to visit my son in USA or will I be able to use an Esta
Any help appreciated. I am 73 and registered disabled and travelling from Manchester to London for an interview would be hard by public transport