Hi, any1 can define me the exact Bus or Rail root for reaching Swansea from London Heathrow Airport Trmnl-3?

A simple query of the National Rail website indicates that the most direct route seems to be a bus from the Heathrow bus terminal to Reading, followed by a train from there to Swansea. The best route, however, may differ depending on the time of day and the day of week, though, so you're probably best running your own search on the National Rail website.

What is, perhaps, more puzzling is the fact that there are several responses indicating that the person asking the question wants to get to Heathrow from Swansea, which is not the case.

I'm sorry, but i don't know.

Roots are part of plants and trees growing in the ground.
Contact National Express Coaches, they have direct routes from most UK cities to the Heathrow Terminals.

Take any London train from Swansea High Street Station and get off at Reading General Station. Follow the signs to the Rail-Air Coach link. The coach sets you down at Heathrow.

I believe that you can get a through ticket from Swansea to Heathrow.

Coaches run from Heathrow Central bus station to Swansea so you will need to get from T3 to the Central bus station.Depending on the coach you choose,you may be required to change at Cardiff. The trains run from Heathrow to Swansea and you will change at Reading. Hope this helps.

Take the frequent rail/air bus link to Reading Station. Then a First Great Western train from Reading to Swansea; they run hourly daily

easy this one go to national express website and look there i know it goes straight throu cos i have friends who live in landore UP THE SWANS

There is a choice of direct public transport options from Heathrow to South Wales and West of England.
There are no flights from Heathrow anymore, flights do operate from Plymouth to London Gatwick but this is not really a realistic option for Heathrow.

National Express coaches run direct services to most major towns and cities in the West & South - West. The National Express coach network covers nearly every town and city in England and Wales, so chances are there is a connecting bus if there is no direct service.
The rail network again serves most major towns and cities in the region. There is no direct train service from Heathrow, you either have to go into London or better and cheaper catch the RailAir coach to Reading, the first stop for trains to the west of England originating from London's Paddington station.

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Example Heathrow services Coach Rail
(Rail Air coach Heathrow-Reading)

Swansea 4 hrs 30mins
Every 90-120 minutes 3 hrs 45 mins
1-2 Trains Hour

Rail Heathrow - West Country & Wales
There is no major mainline station at Heathrow. The main railway line to the West Country starts at London's Paddington station, and passes a few miles to the north of Heathrow.

The journey times are thus compromised by the need to take a shuttle bus (see below) to the nearest station at Reading - a 25 mile motorway journey.
Railways are privatised in the United Kingdom. You may use several companies travelling from Heathrow, but all are integrated for ticketing purposes.
Prices are very complex, normally the best fares are advance purchase, if you pay on the day it can be very expensive.

Use the 'trainline' link right - for timetables and available fares.
RailAir Coach - Heathrow to / from Reading
To avoid making the time consuming journey into London, there are two Rail Air Coaches.
The shuttle Rail Air coach from Heathrow to Reading leave from outside Terminals 1,2 and 3 every 20 to 30 minutes.
Railair Official Web Site