I hope you are well and apologies for the delay in responding.
This is a really good question and one I hear a lot. You may get different responses from other mentors but it really is what works best for you at the end of the day. My advice is to not wait for advertised roles, as it may be too late by the time any opportunities become available. I would make contact with as many companies, departments or individuals as possible so you can start to build a relationship with them early on. My advice is if you know an area or a role you are interested in then be clear with your intention. You mention your goal is to work in tv or film. Do you have a specific area or role that you are interested in? For instance, would you like to be a writer, director, camera operator? It is absolutely ok to not know as well, but then at least you can be open to all opportunities that become available.
Start a new thread on here even, saying you are looking for work experience and if any become available then you would love to be considered for the role. It might help others or there maybe other people in your position that found work experience via another method.
We have had a couple of students on the academy that got offered work experience and are now working in the industry off the back of those opportunities. If there is a thread on the Crew Room where you say what you are looking for and for when we can all keep an eye on it and when anyone has an opportunity they can contact you directly. I manage a studio and we will be looking to give work experience opportunities next year as well so I will definitely consider you once I know what you are looking for.
I hope this helps, but please come back to me if you need anything else or if you need me to go into more detail on anything.