The toilet bowl is leaking - is it worth fixing it yourself? 

Is it difficult to carry out such repairs? Who can give advice?

Well, it would be nice to understand how serious everything is. But in general, there are already instructions on the Internet for all occasions. Just find something similar to your situation and go ahead.

The work itself may not be difficult, but you need experience, and you don't have it. Of course you can find all the solutions on the Internet, but I would not advise it. For any work there is a specialist, and the desire to save money on it can lead to the fact that at night you'll be looking for an emergency plumber to fix what you have done yourself.