Question: My mom wants to do baking but her oven doesn't have bottom heating element. It only has an element on top, with a fan at the back.

She told me that she can't make me a good pizza or cake without it.

Is there any way around?

Answer: 
Many modern ovens seem to have unusual element configurations, but with a fan it makes no difference, just use as the oven manual indicates

Cooking a pizza in any domestic electric oven is tricky, as it requires more heat than an electric oven can generate. Using a metal or stone slab helps
I have a similar type of oven. For basic baking (cake/brownies), I started turning the temp on the oven down about 20 degrees and baking the items for the max time. That seems to be helping. 

HOWEVER, I am still struggling with pizza and pies (thus searching the internet, and stumbling onto this thread). 

I might try the pizza stone method...