LONDON (AFP) - Outgoing British prime minister David Cameron admitted it had not been an "easy journey" as he left office after six years on Wednesday wishing his country "continued success" in its post-Brexit future.

Speaking outside the premier's Downing Street office before making the short journey to Buckingham Palace to tender his resignation to Queen Elizabeth II, Cameron said: "It's not been an easy journey and, of course, we've not got every decision right but I do believe today our country is much stronger."

In his final question and answer session in the House of Commons, Cameron said he would "miss the roar of the crowd and the barbs from the opposition" that came with the job he has held since 2010.

Pointing wistfully to the capricious winds of politics that abruptly ended his career, he said: "I was the future once."

Cameron, 49, quit after Britain voted to leave the European Union in a June 23 referendum he called in an attempt to stop his Conservative Party "banging on about Europe" but sensationally lost.

Flanked by his wife and three children, he wished Britain "continued success".

Earlier he imparted some advice to Theresa May, his long-time interior minister who will be installed as premier later Wednesday.

"My advice to my successor, who is a brilliant negotiator, is that we should try to be as close to the European Union as we can be, for the benefits of trade, of co-operation and of security," he said in parliament, with May sitting beside him.

After accepting Cameron's resignation, Queen Elizabeth will receive May, the new Conservative leader, and task her with forming a government.

The 59-year-old will be Britain's second female prime minister, following in the footsteps of Margaret Thatcher, her fellow Conservative with whom she has inevitably been compared.

The steely vicar's daughter faces a major challenge in trying to negotiate an amicable divorce from the EU following the shock vote for Brexit, which she has vowed to make a "success".

The daughter of a Church of England pastor, May is a cricket fan with a sober demeanour who lists her hobbies as cooking and walking.

She is well liked in and around Maidenhead, the well-to-do commuter town west of London she has represented in parliament since 1997.

Martin Trepte, editor of the Maidenhead Advertiser, the local newspaper, said: "She's a mature, grown-up, no-nonsense politician. She knows her stuff." A tough-talking interior minister for the past six years, May is something of an unknown quantity internationally, although she has received ringing endorsements from party colleagues and a normally sceptical British tabloid press.

European Council president Donald Tusk said he looked forward to a "fruitful working relationship" with her.

But her continental peers have also said they expect her to move quickly to implement the referendum result, with Germany's Angela Merkel, France's Francois Hollande and Italy's Matteo Renzi announcing they will hold a summit in August on the matter.

May has indicated she will not be rushed into triggering the Brexit procedure.

She is expected to begin announcing her cabinet choices later Wednesday, including a minister in charge of negotiating a new trade and travel deal with Europe.

One of the casualties of Wednesday's transition of power could be finance minister George Osborne, a Cameron loyalist. May has been sharply critical of his legacy.

Women are expected to secure several top jobs, with current energy minister Amber Rudd and international development minister Justine Greening tipped for lead roles along with Foreign Minister Philip Hammond and Brexit campaigner Chris Grayling.

Friends of former London mayor Boris Johnson, who had been hotly tipped to succeed Cameron but declined to run at the last minute, told The Daily Telegraph newspaper he also hoped to play a "significant role".

Investors will be watching May's first days in office closely.

The Bank of England will announce Thursday whether it will cut interest rates for the first time in more than seven years to curb economic fallout from Brexit.

May campaigned as a safe pair of hands who will help bridge Conservative Party divisions exposed by the referendum and restore investor confidence.

Her other mammoth challenges include weaving new trade and diplomatic alliances beyond the EU and keeping pro-EU Scotland from bidding for independence.

"Brexit doesn't mean Brexit for Scotland because Scotland didn't vote for Brexit", Scottish First Minister Nicola Sturgeon reiterated Wednesday.

"For us, Remain means Remain." In a good-natured session of parliament, Cameron took potshots at embattled main opposition Labour leader Jeremy Corbyn, who faces a bitter leadership battle of his own.

"We got on with it, we've had resignation, nomination, competition and coronation - they haven't even decided what the rules are yet!" Cameron said.