If you have been sexually assaulted or abused you should report it to the police immediately, although you are not obliged to do so by law. However, reporting it to the police is very advisable and important as they will try to find the person who attacked you and, therefore, perhaps stop them from hurting anyone else. The police can also make sure you get all the support possible, from both themselves and other specialists. You can ask a friend or relative to go to the police with you - many people find it helps not to be alone.
The Victim Support Line charity has a number of local schemes. They can help you talk through your feelings and support you in any practical decisions you need to take.
The Avon and Somerset Constabulary website tells you how the police can help you if you have been sexually assaulted or abused, or if anyone you know has been assaulted in this way. It explains step by step what happens after you report the crime to the police, and what they (and the people and organisations you can be put into contact with) will do next.
The UWE Counselling and Psychological Service, 3F, Frenchay Campus, tel. (0117) 32 82558 may also be able to provide you with support if you wish to talk to someone about your experiences.