The revenue information requested can be found in the Trust Statement section of the published HMRC Annual Accounts:
https://www.gov.uk/government/publications/annual-report-and-accounts-2012-13--3 (see note 2.7 and 2.8 of the 12-13 Trust Statement).
The following table provides the cost of collection information for 12-13:
|Capital Gains Tax||£47,712,401|
NB: The Expenditure is not published externally to HMRC e.g. in the Annual Report or Pocket Briefing.