1.sorry, on several days coming up there are again STRIkes on parts of British rail and this will/may effect also €*-they seem to rearrange their offer. A quick google will lead to more. But sometimes strikes are far wider as told initially and as there are huge staff-shortages and high inflation at the mo workers have much to grumble about.

2.pass cover nr: use special form and DO indiciate day of travel-due to also staff shortage/too much work ´service'tries to handle them in order of urgency. This request is very common.

You can ALTernative call sncf via their 85 = /en/ line as they do not ask for this nr. THis is FRench rail so they are also the 1st to also arrange TGV to the Swiss;

HInt: you can save a bundle by using TGV only IN FRance, get off at last stop and use local train into the Swiss a few mins later. Supplmt for cross-border is much, much higher as for only In FR-these age old tricks seem to completely forgotten.

You can call  b-europe and make the reservation. No need of Pass Cover Number.

The phone call is rather expensive.

https://www.b-europe.com/EN/Contact/Contact-Centre

The best way to make reservations for French trains is to call SNCF. No need of Pass Cover Number. 

https://www.sncf.com/en/customer-service/contact-us/telephone

 Press #85 for English, no booking fees, reservations are sent via e-mail

To get your Pass Cover Number, if you still will need it, you need to contact Customer Support through this form and ask for the Pass Cover Number.

https://eurail.zendesk.com/hc/en-001/requests/new

Customer Support is currently overloaded with requests so you will probably have to be patient to get help. Please let Customer Support know what date your travel will start so that they can prioritise your request correctly.