New GM, new poster, new thread. Go be helpful!
Here's my example.
Hello, welcome aboard!
If someone at the table knows the Whoniverse inside and out, you can (a) remind them that the setting will change, "time can be rewritten" and all that or (b) recruit them as a 'consultant' and ask before (and possibly during) the game what they know on a given topic.
I play fast and loose with continuity, introduce new monsters, massively alter old ones, blithely ignore setting points... and so does the show.
Equally, a player who can give a potted history of the Dalek Empire without notes could be great if they wanted to play a character with a lot of Ingenuity and Knowledge to bring their out-of-game knowledge in-character. Possibly a good choice to play a Time Lord.
If the idea is for a one-shot game, pregenerated existing characters is a good idea. Even though it takes me about ten minutes to get a new player to generate a character from cold - maybe fifteen for an alien or Time Lord or somesuch - that's still ten minutes for each player, fine if there are only two or three, and fine for the first session of a series, but a one-shot lets you decide who can do what, tie the characters into the plotline and setting, and the like.
Sound out the players about Doctors, Time Lords, Companions and other character types in advance. If none of the players want to be "in charge" like a Time Lord or other owner or pilot of a time machine, then an NPC like that who takes more of a hands-off role in the adventuring, like the First Doctor, might suit them better than a charge-in-and-sort-things-out hero like later incarnations. An NPC saving the day would be in-character for plenty of Doctors, but would not be so cool at the gaming table.
Equally, you could forego such an NPC and have a MacGuffin like a semi-sentient TARDIS or other uncontrollable time-travelling effect that drops them into adventures and picks them up at the end.
(You could also forego the travelling in time and space part and run something set in a particular location, but that's definitely something to discuss with the players before starting.)
For the timeline, try TARDIS Index File for a terrifyingly thorough breakdown of everything ever.
I also prattle on about possible game types in my rambling Whoblog. Some of it may be helpful, I hope.
One of these days I'll write up a convention or new group-friendly one-shot game and post it online. In the meantime, the adventure book in the rules has two, and there are more to find here on the forum.
Good luck! let us know how you get on.