In October we will would like to travel by train from Basel Switzerland to Paris and then on to London. I know things could change dramatically by October but wanted to know how Covid travel guidelines may impact our trip. Any insight would be much appreciated.
No one knows because it’s 6 months from now. Right now you must wear masks on trains in Germany, but who knows what will be going on in October?
SBB directs you to this page of French Government regulations.
Long and short is that the USA and Canada are now considered "green" countries.
https://www.gouvernement.fr/infocoronavirus/deplacement
use google translate to get this site in English.
Of course, this is as of today. 6 months from now, who knows.