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: 
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...
I know using a cast iron skillet starting off your pizzas on the bottom rack depending on the thickness of the crust for 15 to 25 minutes and raising it to the second to the top for the last 7 to 12 minutes and the cast iron skillet will continue cooking once you shut the oven off to make it nice and crispy... I will absolutely not make a pizza any other way