Wales: London to Snowdonia to Cardiff to London
 

We plan to visit Snowdonia and Cardiff in October. We have tickets into Heathrow and are trying to figure out the best way to get around

Train from Heathrow to Llandudno Junction (via Euston). Given that our flight might be delayed, it doesn't make sense to buy tickets for a specific time in advance, but same day purchases are much more expensive. Can we buy tickets for a specific day but not a specific time?

Rent a car in Llandudno Junction. We plan to explore the area for about a week

Train from Llandudno to Cardiff. Day trips for 2-3 days

Coach from Cardiff back to Heathrow. Is the coach generally on time, so that we would be comfortable scheduling our arrival at Heathrow 2-3 hours before our flight (rather than worrying we'll get delayed in traffic)? This would be on a Sunday, if that matters.

Does this seem a sensible way to proceed?

It seems less expensive to do Heathrow - Cardiff - Llandudno Junction - Heathrow, due to the large spread between same day and advance purchase for the train between Heathrow and Llandudno Junction.

Interesting. You think it is too risky to buy a cheap, restricted train ticket to North Wales because of fear of flight delay. But you are comfortable with staying 150 miles away from the airport on the night before the return flight.

My risk profile would be totally opposite. I would be comfortable buying a train ticket out of Euston timed for about 4 hours after schedule arrival at LHR. But I'd be very uncomfortable staying in Cardiff the night before the flight home unless that flight was late in the afternoon and I could schedule the bus arrival about 4 hours before scheduled plane departure.

No, there is no cost-saving ticket as described in your 2nd paragraph.

Return flight is at 5pm. A 9:30am train from Lladudno Junction should arrive at Heathrow at about 2:30pm (with a few transfers). I can't remember having a problem with fast-track security at Heathrow.

How badly delayed are the trains likely to be?

There are frequent buses Cardiff to Heathrow. How badly delayed are they likely to be on a Sunday morning?

««I can't remember having a problem with fast-track security at Heathrow.««
I don't know what that means. What does one have to be or to do to get access to fast-track security?

««How badly delayed are the trains likely to be?««
The on-time record of Uk train companies is pretty good - most probably achieve a 90% on-time performance

»»There are frequent buses Cardiff to Heathrow. How badly delayed are they likely to be on a Sunday morning?««
Not very likely at all.

I guess my point is, if I miss my advance purchased train to Llandudno Junction, an off-peak ticket on a later train will cost me £78.30. If I miss my flight, a ticket on a plane the next day or on an inconvenient multi-stop journey would cost me $1500 to $2000.

OK -- there are NO trains from LHR to Wales, or to anywhere else besides Paddington station in London. And then you have to get from Paddington to Euston. You'll want to have 4.5 hours (or more) between the flight and train.

Have you considered flying directly from LHR to Manchester and going to Wales from there?

National express coaches will get you to Heathrow from Cardiff easily.
One thing to note, there maybe some coaches that pick up twice in Bristol en route. It may be me but i have always found this to be a real pain as this detour seems to take ages.
Just check the number of stops and the estimated arrival time.

Oh- and Sunday Morning the M4 should be clear so delays should be practically non existant.

Train to paddington from cardiff is really quick, under 2 hours, but there are various fares so check the cost before booking.
I have no understanding of train fares and how to get the cheapest, it confuses the $4it out of me. :-)

Good luck

Muck