LONDON — THE annual fall conferences of Britain's political parties are attracting much more than the usual amount of attention. Almost certainly there will be a general election next year, and people want to know whether the Thatcher government retains the steam to win a fourth parliamentary term - unprecedented in this century - or if it is destined to cede power to a renovated Labour Party under Neil Kinnock.
The ``big battalions'' of left and right last week waited in the wings as the Liberal Democrats, Britain's third party, kicked off the month-long political beauty contest. Party delegates heard Paddy Ashdown, their leader, promise them a long hard slog ahead.
The opinion polls, he told delegates at Blackpool, showed that only 8 percent of the electorate would vote for their party. The next general election, he said, would be a ``staging post rather than a destination.''
Highlighting what the main election theme is likely to be for all the parties, he threw the Liberal Democrats' support behind ``a liberal market, an investment-led market, and a market founded on individual skills and enterprise.''
Mr. Ashdown heads a party that is trying to pull itself together after a decade in which it entered into a disastrous alliance with the now moribund Social Democrats under David Owen. In company with the other party leaders, he knows the next election will be fought on a somber economic field.
Inflation at 10.6 percent is higher than it was when Margaret Thatcher first came to office in 1979. Unemployment is heading back toward 2 million, and the trade gap threatens to match last year's record-breaking 20 billion ($37.4 billion).
Ashdown reflected a widespread yearning for new answers to ``stagflation'' when he demanded that the Liberal Democrats abandon their traditional center-left stance on the economy and embrace market forces.
He stepped out ahead of Mrs. Thatcher and Mr. Kinnock by proposing to privatize the rolling stock operations of state-owned British Rail and to break up British Telecom into competitive units, along American lines.
One delegate at Blackpool described Ashdown's fiery speech as ``inspirational - the most clear-cut statement of our policies in years.'' It needed to be.
Shortly before he gave his platform address, the leader was handed an opinion poll suggesting that four out of five voters had little idea about what his party stands for. Some were even uncertain about its name (it used to call itself the Liberal Party).
The Labour Party, with more than a decade to evolve a new set of policies, appears to have managed to inscribe them more clearly on the public mind. One of Kinnock's officials last week described Labour as ``the next party of government'' with economic, defense, and social policies that would enable it to ``clear up the devastation caused by 11 years of Thatcherism.''
John Smith, Labour's chief economic spokesman, yesterday assailed Thatcher for letting British industry decay and creating widespread unemployment, from the boardroom to the factory floor.
In the last two years, Kinnock has pushed through his party's executive - which now has a majority of moderate members - a set of policies far different from those the British electorate flatly rejected in 1987, when it gave the Conservatives a 100-plus majority in the House of Commons.
Labour, too, has moved a long way toward embracing market economics. It has tamed trade union militants and thrown out the policy of unilateral nuclear disarmament that enabled Thatcher to characterize it as soft on defense.
With opinion polls showing Labour consistently ahead of the Conservatives by about 12 percent, Kinnock at his party's Oct. 1 conference hopes to get full endorsement for the new policies.
Mr. Smith, who is earmarked to be chancellor of the exchequer if Labour wins power, has said Thatcher's enthusiasm for the highly unpopular poll tax is a symptom of the extent to which she was out of touch with the people. Government statistics released last week showed that nearly a quarter of people on the poll tax register had refused to pay it. Kinnock is promising to replace the tax with a measure that would hit the rich harder and soften the blow for poorer people.
When he faces delegates, he is expected to unveil a new aspect of Labour policy: emphasis on family life. A Labour official said Kinnock believed there was a clear link between family breakdown and family poverty.
As the incumbent, Thatcher has the advantage of being able to decide when the general election is held (the latest possible date is mid-1992, but British parliaments seldom run their full five-year term).
At the Conservative conference to be held in Bournemouth Oct. 9, Thatcher is expected to place her own stamp of authority on the proceedings and try to make it plain that she is still a dominant leader.
During September, opinion polls showed Thatcher's popularity rising marginally, mainly because of her tough stand on the Gulf crisis.