For legislation, case law and commentary (including articles in legal journals) holders of an Oxford SSO should use the three databases below
UK Asylum and Immigration law
Halsbury's Laws of England at KZ1 will give you the "busy practitioner's overview" .
SOLO may show that some titles are in the Law Reserve Collection. More, in depth treatments, will be found on open shelf in the shelf mark range KM176 - KM177.7
To find more in depth treatment on this topic do a subject search in SOLO using:
Asylum, Right of
Emigration and immigration law
Refugees -- Legal status, laws, etc
Deportation
Citizenship
Immigration and Asylum Law by 
Administrative Justice and Asylum Appeals : a study of tribunal adjudication by 
The Law and Practice of Expulsion and Exclusion from the United Kingdom by 
The Human Rights Act and the Assault on Liberty : rights and asylum in the UK by