Although the immigration rules do not require unaccompanied students to show that accommodation has been arranged, your place of study may have given you information about its availability, and you should bring this to the attention of the ECO. If your family is coming with you to the UK, you will need to show that there wills adequate accommodation for them. If your place of study cannot confirm that family accommodation will be available, you may have to consider traveling to the UK alone and making arrangements for your family to join you when you have found somewhere to live.