Before panicking do check on the various operator websites what actual services will be running. Many operators are running a timetable and you may be able to get  close to home via alternative operators.

We've checked on all possible carriers and there's no trains coming for Wales until Sunday 8th January 

GWR are offering a train service from Paddington to Cardiff until 15:14. Look at GWR Strike information for complete details.

Our Eurostar gets into London at 16.39 .…

Unfortunately Cardiff is still quite far from Carmarthen 

Then you are short on options, National Express or  Megabus to Swansea and taxi from there or get a hotel somewhere in London and use your pass to travel the next day to Cardiff and use local bus from there.

There is the 1 a day TrawsCymru T1C route from Cardiff - Carmarthen at 17.20 but you’d have to get to London much earlier to get  a train to Cardiff for that.

If you get stranded, then the operators have to provide accommodation and transport at the earliest convenience at no extra cost.

This follows from EU Regulation 1371/2007, which has been transposed into UK law.

All reports would suggest that In the case of strike days it is near impossible to get anything out of them on the spot in regards arranging or paying for accommodation or alternative travel.

A subsequent claim might result in a payment, particularly in a case like this where an inbound international rail passenger with no other option is stranded but I would expect it to require considerable persistance and possibly escalating as far as legal action.

I often hope that someone does this, so as to create some legal precedence.

Passengers however more often than not don't know which rights they have and the railway staff isn't always much better informed.

Thanks so much for your replies , there are 5 of us travelling 3 kids 2 adults & i have an illness/disability , if i was travelling on my own & was younger etc I'd just wing it .…but an etc night in London or Cardiff for 5 of us , getting to the accommodation etc & then extra long journey time the next day will really take it out of me & the costs will just escalate even more, we've prebooked a taxi that we can cancel if the strikes get called off , it was £550 and went on the emergency credit card , we will have to see if we can claim on our travel insurance,  and I fully intend to make a claim against the rail company,  a 1 day strike I can understand but not from 2nd January to the 7th /8th with no option for people to get home especially when we live so far away .

We live and learn x

Here is what I would do in respect of trying to get some of your money back.

1. Contact your insurance company for advice as to whether you are covered for strike related expenses - be specific and follow up by email. I think this may be your best option.
2. Contact GWR ideally by email so you have a paper trail. The circumstance you are in is pretty unusual. There’s no harm in ringing them as well as they ought to create an enquiry reference number. Your best chance here is that they offer an ex-gratia payment but I think this highly unlikely (see below).
3. Unfortunately there are literally thousands of stations in the UK that will not have train services for several days (mine included) so I am not hopeful that the national conditions of carriage will make them liable. However, you will need GWR to formally decline your claim before you can take your case to the Ombudsman.
4. Contact the consumer group Which for further advice if you contemplate challenging the decision of the Ombudsman, assuming he rules against you.
5. Please keep us up to date with what happens and the very best of luck!