Great Western Coffee Shop

Is there a definitive list of what tickets can / cannot be bought at TVMs (ticket vending machines)

YES:
Tickets for immediate travel from the station at which the machine is located to any other station
Tickets on railcards
Weekly season tickets were an ID card is held already

NO:
Tickets for future dates
Tickets from other stations
Weekly season tickets were an ID card is not held already

PLEASE TELL ME:
Rangers and Rovers
Groupsave tickets
Longer season tickets
Tickets that include something else such as admission to Steam in Swindon

Only interested in GWR stations?

Some operators TVMs can issue tickets with a different origin than the location.

Ideally I'm looking for guidance for passengers joining trains in Wiltshire - so essentially GWR stations, but if the guidance covers Salisbury and Tisbury (is there a machine there?) too, so much the better.  Not too bothered about what the TVMs at Machester Piccadilly can do.

P.S. Can the machines at Heathrow still only offer a limited range?  Personal question for me for Friday morning!

Tisbury does indeed have a ticket machine .

Unless they've been updated recently, the Heathrow Express passenger operated machines at T5 are like the machines at Paddington - LUL style machines vending a very basic range of tickets.  I would safely assume the other terminals all have similar machines.

In T5 only, the London Underground machines are actually operated by Heathrow Express.  They can even top up Oyster cards, printing a LUL receipt on Heathrow Express stock.  Again, selling the limited range of destinations usually available from LUL.

I am not sure if annual season tickets can be bought or replaced at ticket machines. I have had to replace mine several times as it eventually wears out at the barriers so have gone to the manned ticket offices at Bath or Temple Meads to replace it. Im not sure if the ticket machines have somewhere where you scan the barcode on the photocard.

They can only issue weekly season tickets and cannot replace tickets.  There is no barcode scanner - you have to key the photocard number in using the touchscreen.

Some TOCs (e.g. Southern) allow monthly tickets to be renewed at ticket machines.