If there is a queue at the ticket office, can I still board the train without a valid ticket?

No, it is your responsibility to allow yourself enough time to purchase a ticket before travelling with c2c.

Automatic self-service ticket machines are provided at the majority of c2c stations as an additional method of purchase; tickets can also be bought in advance of travel from ticket offices, the telesales office on 0345 744 4422 (select option six) or via our website or app. If purchased on the app, tickets can be loaded directly to a c2c Smartcard.