When playing on the public server I dematted my TARDIS for the night to make sure it was safe from other people's hands, when I logged back on the next morning however, I would go to the demat lever to land but when I used it it said it was dematerializing again then it would not land again, requiring a mod to summon it for me.

Do NOT demat and leave it for the night that is how players glitch their tardises... Ask an online staff member to summon it for you. 

I repeat do not demat your tardis and leave the server in the future. Thank you.