St. Pancras to Brussels is an outbound trip.

There MAY be the tiny small chance that they give you some compensation for it-do not count on that. In fact that may look more like: use that Virgin-nownewname train to LON labelled as on 3d but use on 2nd. You have to plea with them to get that done-or not. Perhaps there are some general strike rules for tickets?

IF not (there are likely people who know far better as me how that works now that EU-rules apply no more-- Brexit) do the sums: what works out as best value-fly back to MAN from somewhere at end-or if die hard ´allonrails!!´what is lowest extra to pay in fares: to LON, or coming back (but use €* is then also impossible as you need to have global pass valid in all countries on that day.

When there are strikes in the UK there has been information about the possibility to use the ticket for date of the Eurostar travel to travel within UK the day before/after the strike. You can search for previous post on the subject in the Community. 

You need a valid travel day to travel on the Eurostar. 

This is the official page for information for passengers on the ongoing industrial action.

https://www.nationalrail.co.uk/service_disruptions/industrialaction.aspx

Details are currently only published for earlier dates but there is no reason to assume it won’t be exactly the same ticket acceptance for future strike days.

It is quite clear that tickets for the strike days will be valid on the day/s before and after. There is no exceptions or caveats given, your interrail is just as valid as any other ticket for this rule.

Under no circumstances should you add the replacement travel day to either a mobile or paper pass if you will also need to use the pass on the strike day.

Enter the strike day on your pass and enter the equivalent of the trains you take for that day, if challenged explain that to add the correct day will mean using an additional date and you are availing of the agreement to allow tickets for strike days to be used on the day before.

I would say it is unlikely you will have any issues with this, the staff are in dispute with the Government and their employers not their passengers so it is not in their interest to harass passengers over strike day tickets.

Thankyou. That is very helpful.

I’ve booked a hotel for the night in London and can now have a day sightseeing in London.

That would have been my preference anyway if the Inbound/Outbound restrictionss weren’t so restrictive.

Just to add that you should keep an eye on your Eurostar plans too. They are not the subject of strikes by their own staff but the action against Network Rail can cause disruption to their services, more likely the possibility of reductions/delays rather than outright collapse of the service.

https://www.eurostar.com/uk-en/travel-info/service-information/eurostar-travel-updates