Recently there have been a few questions about the time limits for abortion over here so, for purposes of clarification, here it is.
Abortions for 'social' reasons are permitted up to and during the 24th week of pregnancy. Abortions for foetal abnormality or sever maternal health problems are avialble up until birth. This is stated quite clearly in the abortion act 1967 as ammended by the human fertilisation and embryology act 1990.