public transport Cardiff & north Wales

Every 2 hours there is a direct Transport for Wales train from Cardiff to Conwy.
https://tfw.wales/
There are regular trains from Conwy to London Euston (Transport for Wales to Chester, Avanti Chester to London), and two trains per hour from London Paddington to Cardiff. (First Great Western)

Assuming you are flying into London probably easiest is either train into Paddington/train Paddington to Cardiff- or even easier the hourly National Express coach from Heathrow Airport to Cardiff- easier when arriving jetlagged.
https://www.nationalexpress.com/en
There is no good reason why you couldn't take the same route back.

A question isn31c...

Would it be better to catch a train to Llandudno Junction rather than Conwy? Would there be a better choice of trains?

Thanks - that's helpful.
I'm not going back to Heathrow, but on to Brussels hopefully on Eurostar, so will want to return to Euston Station.

If you are going to Brussels by Eurostar it would be best to go Heathrow to Cardiff and then train to Conwy and then Conwy / Llandudno Junction to London Euston for the short transfer to St.Pancras for the Eurostar.

Note that all trains stop at Llandudno Junction - which is just over 1 mile east of Conwy. Avanti West Coast also have direct trains from Llandudno Junction to Euston. Also consider taking a look at the historic English city of Chester - which is near the Welsh border. If going back to London Euston, you may find it cheaper to book an advance ticket from Crewe rather than north Wales and then just match up a connection from north Wales/Chester.

If you just want to get quickly back to Brussels from N Wales, Ryan Air has cheap flights from Manchester Airport - which has direct trains from north Wales. However, these flights go to Charleroi Airport which is to the south of Brussels.

The answer to Wasleys is a no (re- Cardiff to Llandudno junction), that this was looked at last week. There is only a 2 hourly Cardiff to North Wales service (the other hour it is Birmingham to North Wales) and all the ex Cardiff and ex Birmingham stop at Conwy.
On the other hour you could catch a West Wales to Manchester service at Cardiff and change to the ex Birmingham at Shrewsbury.
I deliberately said change to Avanti at Chester as only some Avanti services go to Holyhead. There are quite a few more which start at Chester, for Euston.
Brussels Airlines and British Airways also fly from Manchester to Brussels.
If travelling to Brussels then when booking on the Avanti website book a through fare from Conwy to London International (Civ) (LNE) as that will protect you if there is a delay on Avanti- you will get a free transfer onto the next Eurostar as long as you originally allowed the MCT at London.
If you merely book to London Euston and then a separate Eurostar ticket you don't get that protection, and would have to book a new Eurostar ticket.

Thanks for the clarification isn31c. So many people elsewhere recommend getting off at Llandudno Junction for Conwy, I did wonder.

isn31c - I don't know what this means "as long as you originally allowed the MCT at London." What is the MTC?

Thanks

Lots of good info here. I do want to take the train for environmental reasons - and I like European trains :-)
That said, I read that Eurostar is already booked solid for summer. I'm looking at late September, but see that some time slots are already listed as filled. I want to reserve, but want to be sure I allow myself enough time to get from wherever in Wales to London and make the transfer...
Thanks

The train from Cardiff goes to Paddington, but then lists "London Underground" for the last 13 min to Euston. Does anyone know how that works? Is it included in the ticket from Cardiff? The listing for the Wales train sight does list the final destination as Euston. I might need an early train in order to make the connection work as the Eurostar is already 'unavailable' for the date I'm looking at for the one midday train. I don't want to get to Brussels too late as I hope to go on to Bruges...

Thanks

MCT is Minimum Connecting Time. So you have a minimum 90 minute check in now at Eurostar (due to post Brexit checks), plus the time to walk down the street/take the tube/whatever between Euston and St Pancras stations, so realistically 2 hours to connect (105 minutes at a pinch). If connecting from Paddington then change that to be Cardiff to London King's Cross and yes, the fare includes the tube (Circle or Hammersmith and City from Paddington). Kings Cross and St Pancras are a joint tube station.
I know what it says but the sensible time is 40 minutes from Paddington to Kings Cross so 90 +40= 130 minutes MCT.
https://www.eurostar.com/uk-en/travel-info/your-trip/check-in.
The Eurostar is running to reduced capacity, but it seems odd to me that the 1pm is not available every day but the 1100 and 1500 each day have good availability- I wonder if the 1pm is actually suspended.
For an extra £12 beyond the Brussels fare you can book to any Belgian city. You would need to check the Belgian Railways (SNCB) website to see if that is or isn't a bargain, or whether you're better off rebooking at Brussels. Brussels to Bruges for instance is E16 so in that case it is worth it.

If the route shows "then underground" it would be included in the ticket
Check price to Paddington as may be cheaper to do this then pay for Underground
I think you can still book to Any Belgium station on Eurostar

edit
just had a quick look and seeing Advance Single for a date in April at £29.50 Cardiff to Paddington and £32.50 to St Pancras
Underground fare is £2.70 Off Peak using Oyster or Contactless card.

All of this is very helpful - thanks!