The announcement is a boost to the outlook for London Stock Exchange listings after earlier this month ready meals supplier Bakkavor <BAKK.L> and telecoms masts firm Arqiva <IPO-ARGL.L> both pulled deals.
Bakkavor reversed that decision just a week later, after cutting its share price.
Founded in 1982, Sabre generated gross written premiums of 197 million pounds in 2016 and said it intends to maintain its focus on the UK private motor insurance market.
The listing would value the whole company at around 600 million pounds, a source familiar with the deal said.
Sabre's private equity owner BC Partners is looking to list the Dorking-based firm in London following an unsuccessful joint approach from U.S. investment firm Centerbridge and Qatar Reinsurance Company, sources told Reuters in September.
BC Partners took a majority stake in Sabre in 2013 in a 240 million-pound deal.
The company, which is behind the Insure 2 Drive, Go Girl and Drive Smart brands, abandoned talking with prospective buyers in favour of a listing.
Barclays and Numis Securities Limited are acting as joint global co-ordinators on the deal.
(Reporting by Lawrence White, additional reporting by Ben Martin, editing by Louise Heavens)