Horlick's mother, Suzanna Czyzewska, was born in Warsaw in 1939. Czyzewska's parents fled to Russia when the Nazis invaded Poland, and when liberated, they fought with the British in the Middle East. After the war, they lived in Kenya, where Czyzewska was brought up. She moved to the UK when she was 19 and married Horlick's father when she was 21. After having two children, Nicola and then her brother Christopher, Czyzewska went to the Liverpool University School of Architecture and qualified as an architect. Horlick's father, Michael Gayford, was a Liberal candidate in the 1970s for Wirral. Horlick's parents lived in Puddington Old Hall, which is an historic Tudor house.
Horlick attended the independent Kingsmead School in Hoylake, Wirral between the ages of six and twelve. She was one of four girls amongst 300 boys initially. She then boarded at the independent Cheltenham Ladies' College in 1973. She stayed for two years then went to Birkenhead High School GDST. She also spent some time at the Phillips Exeter Academy in New Hampshire, USA on an English-Speaking Union exchange scholarship. She gained nine O levels, four A levels and an S level. She gained a place at Balliol College, Oxford in 1979 to study Law, and graduated in 1982.
Between 1982 and 1983, Horlick worked for her father in the family business. She then joined S. G. Warburg & Co. as a graduate trainee in 1983, starting in the investment management business, which later became Mercury Asset Management. She was appointed a director in 1989. She joined Morgan Grenfell Asset Management in 1991 and was appointed Managing Director of the UK investment business in 1992. During the period that she managed that business, assets under management rose from £4 billion to £22.5 billion.
She set up SG Asset Management in 1997 and Bramdean Asset Management LLP in 2005.She is currently the Chairman of Rockpool Investments LLP and the CEO of Money&Co. She also has a film business called Derby Street Films. Rockpool has its offices in Victoria and the other businesses are based in Mayfair.
Bernard Madoff scandal
Bramdean Alternatives, part-managed by Bramdean Asset Management LLP, had invested about 9 per cent of its assets (about £10m) with the US trader Bernard Madoff by December 2008. Horlick was not responsible for the hedge fund portfolio. This was managed by RMF, which was part of Man Group.  On 11 December 2008, Madoff was arrested and later charged with criminal securities fraud. As a result, Bramdean shares lost a third of their value. In an interview on the BBC's Today programme on the Monday following Madoff's fall, Horlick blamed the U.S. Securities and Exchange Commission for the loss.
Horlick has been described as Superwoman in the media for balancing her high-flying finance career with bringing up six children, Georgina, Alice, Serena, Antonia, Rupert, and Benjie. Her eldest daughter, Georgina, died of leukaemia in 1998 when she was 12. 
She married Timothy Piers Horlick, whom she had met while at Oxford, in June 1984, when she was 23. They separated in December 2003 and divorced in 2005. Her second marriage is to Martin Baker, a financial journalist, on 8 September 2006. They had met in March 2005, when he interviewed her for the Sunday Telegraph.
- "Fifty lessons: teamwork takes all kinds". Daily Telegraph (London). 30 June 2005. Retrieved 5 August 2013.
- "Banks hit worldwide by US 'fraud'". BBC News. 15 December 2008.
- "The Madoff Case: A Timeline". The Wall Street Journal. 6 March 2009. Retrieved 1 June 2011.
- Foley, Stephen (13 December 2008). "'Superwoman' stung by hedge fund guru's '$50bn trading scam'". The Independent (London).
- Business profile: The mother of all fund managers, interview in the Sunday Telegraph 13 Mar 2005
- "City superwoman reveals marriage joy". Daily Mail (London). 10 September 2006.
- [http://www.ft.com/cms/s/2/cf11d2c8-9a38-11e1-aa6d-00144feabdc0.html#axzz2RB1epVUN Nicola Horlick now, profile in FT.com 12 May 2012
- Rumsey, Lulu (August 2013). "Horlicks goes to Hollywood". Residents' Journal (4).
- Sunday Express November 2008
- The Times May 2008
- Daily Mail January 2008
- Money Marketing June 2007
- Getting married in September 2006
- Sunday Times May 2006
- The Observer September 2005
- Ellesmere Port Pioneer July 2003