I agree with Casdon, spread your journey over 2 days to allow enough time.
Arthritis has changed me from a very independent, adventurous person who loved travelling, to someone who is limited by disability. I just didn’t take this change in at first. I’d describe it as changing from a ‘can do’ attitude to a ‘can’t do’ attitude. It’s a very hard adjustment.
On a practical note, I had to start using a walking stick, and I found people on public transport readily offered assistance when they could see that I was physically challenged.
Good luck with the trip - I hope you get there.