It is perfectly possible to work during the GDL and LPC - I have worked up to 15 hours a week on both (and I got a distinction in my GDL) and still work now, during exam revision. It’s all about time-management. Plus the money is necessary!
Working that much may not be appropriate for everyone but it is certainly possible! It doesn’t need to exclude your social life either.
I know several people who worked on GDL and LPC and manage fine. On the BVC it it likely to be more difficult - a few hours a week shouldn’t affect your grade though, and may even be a welcome break from studying!
Always remember that your univeristy studies are paramount, and make sure your employer is aware of that if necessary. Good luck finding a job.