One of the best (but not the only) places to find and apply online for apprenticeships is through the official (government sponsored) 'Find an Apprenticeship' service at www.apprenticeships.org.uk.
Having registered a user account (you need a valid email address) you can manage multiple applications through the portal with a minimum of fuss. Below are some top tips to ensure a trouble-free experience:
Use your personal email address >>
Use your own email address rather than your school one to ensure you have continued access to messages.
Don't register twice >>
Try not to create more than one account as you may not remember several usernames and passwords. Having several accounts would make it difficult for you to manage your job applications.