The eticketting website will be selling tickets to Ambassadors from 3pm on Saturday 7th May and the ticket office will be open from 10am - 4pm on Sunday.
Ambassadors have until Friday 13th may to secure their seats.
The home leg of the play off will be second because Cardiff cannot finish below 4th place. Fans are urged to purchase online where their membership cards will be activated.
For full details click here
Play off dates and opposition are still subject to final clarification.