The leaving care service is made up of personal advisors who work with young peoploe aged 18-21 ( or 24 if you remain in further education) who have left care.
You can use drop -in centre anytime you want ( just remember though, if you want to see your worker, it is best to arrange a time as they might be out with someone else!).
Once you are 18 and leave care, your social worker will make sure your case is transferred to the leaving care and that you are allocaed a personl advisor.
Personal Advisors are NOT social workers but they perform similar role, like helping you with benefits, accessing jobs, education, traning etc.
The guide to Leaving Care