Sorry guys, need help about how to use "trainline"?

Sorry guys, I'd been tweet with trainline staff, I see this link

User Posted Link

they said I can't get e-ticket or mobile ticket, that's ok, I can still purchase from the website, print it out and then take it to get the train, but their staff said

"Yes however Heathrow station does not have collection faculties so I would recommend booking your tickets from London only..." I don't understand what it means, did I need to purchase tube ticket? For example I want to buy the ticket of 13:14 16:27 to Norwich whcih is GBP 14.10...

Posted By: XXL16, Sep 29, 09:51:06