Ah. Bristol to Swindon is an option. Bus it to Temple Meads and then Bristol to Swindon via Parkway and back via Bath. Thanks for this.

Mark

 
Past experience of Melksham to other-side-of-tunnel stations tickets is that they ARE valid via Swindon and BPW, though tickets to this side of the tunnel - such as Melksham to BPW - are NOT available via Swindon.   Looking at GWR tickets - it MAY be that a Newport is needed ... and by that time you're getting more costly anyway.

Your other option would be a single BTH to BRI then a return from there to Swindon - valid out via BPW and back via / to BTH.

 
Thanks for thinking of the 19 bus - that might be good tho its issue is that it tends to hit congestion. (And I'd still need another rail ticket from Swindon back to Bath).

Melksham to Severn Tunnel Junction... I would never have thought of that. A bit wary though that 'Any permitted route' perhaps might not  include via Swindon (though it would be sensible if it did). Putting that journey into the National Rail planner and explicitly setting a 'Via Swindon' constraint results in this:

'This route may require multiple tickets, please replan your journey'.

On the national rail site, that presents itself as a link according to the cursor (which turns into a hand)... but whatever it is isn't clickable...

The 'May' in that sentence... perhaps it implies that even their journey planner is uncertain as to whether its valid or not.

Mark

 
Would the First Bus service 19 between Bath & Bristol Parkway (1hr 40min normal journey time) + BPW<>SWI Off Peak Day Return £14.60 (c. £9.70 with a Railcard) work for you?

 

From Melksham, I would buy a Melksham to Severn Tunnel Junction return as that's valid via Bath or Swindon. You would need to add a Chippenham to Bath Single ...

 
Needing this ticket for... reasons, and would be happy to discover something more cost-effective than three singles.

Mark