Jan 19 (Reuters) - The cost of a comprehensive car insurance policy in Britain is expected to be volatile this year, after rising 5% in the final quarter of 2021 as more drivers took to roads on easing COVID-19 curbs, a survey showed on Wednesday. Motorists now have to pay 539 pounds ($734.06) on average for their comprehensive car insurance premiums, according to the latest index from price comparison site Confused.com in association with insurance broker Willis Towers Watson (WTY.F). Car insurance premiums had fallen for 12 months through to the autumn of 2021 as lockdowns kept motorists off the roads and competition in the UK car insurance industry intensified. Prices are expected to inflate even further over the coming months as the pandemic has heightened issues related to Brexit, Confused.com Chief Executive Louise O"Shea said in a statement. More volatility is expected with insurers competing to maintain margins as they adjust to the new fair pricing rules, said Tim Rourke, the UK Head of P&C Pricing, Product, Claims and Underwriting at Willis Towers Watson. Britain"s financial regulator in May had said it would move to protect consumers from so-called loyalty penalties in motor and home insurance, potentially saving an estimated 4.2 billion pounds over 10 years. read more "How insurers respond to the new rules through pricing and product strategy will determine just how turbulent the next few months become," Rourke said. West Central London remains the most expensive place in the UK to buy car insurance, with an average premium of 1,079 pounds according to the survey, while Llandrindod Wells in Wales offers the cheapest ones at an average of 326 pounds. Motor insurance premiums fell by 6% in 2021, the survey said. ($1 = 0.7343 pounds)