I wouldn't worry about 3D for now.
all you really need to know is After effects, photoshop & illustrator.
anything else is a bonus. Don't spread yourself too thin, just learn AE inside & out and get a shit hot reel together.
some motion graphics people will learn a bit of 3D to top up their skillset once they have worked in the industry a while to give them a bit of an edge...and some studios will now ask for a bit of knowledge in 3D, BUT most places will have a seperate 3D guys so I wouldn't worry about trying to learn 3D at an early stage.
If at some stage you do decide to get into 3D and you're into it, there is the issue of which package to learn. Maya is a bit of a beast, and it will take a lot to get to grips with. Same with 3D max. It will take a bit of commitment to get to a level where you can use these effectively.
the good news is cinema 4D integrates really well with After effects and is MUCH easier to learn. A lot of the studios (particularly in LA) are using Cinema 4D now. Not sure about the UK, but the studios in Toronto haven't really picked up on cinema 4D, so I haven't bothered much with it.
c4d is suited for people who just want to add an extra 3D element to their motion work/reel rather than fully getting involved in 3D animation.