If you are under 16, Social Services have a duty to provide emergency accommodation for you. This may be with a family or in a hostel, B&B or similar.
The local councils have a duty to help with emergency accommodation for over 16s – the amount of help varies from council to council but may only be the telephone numbers of the nearest night shelter or homeless shelter. You will probably have little choice in where you can go, and will usually have to make your own way there. Also, don’t expect emergency accommodation to be of a high standard – it really is for emergencies only, when you really can’t find anywhere else to stay.
If you're in a difficult situation, you can access the No Limits advice centre or the Health and Wellbeing drop-ins within your school or college for support and referrals over housing and other issues.