Liberal Democrat leader Nick Clegg is facing a defining party conference this autumn in which he is likely to try to push the party to the centre ground on issues ranging from the economy and university tuition fees to nuclear power and the retention of a limited independent nuclear deterrent.

The party conference in Glasgow in September will tackle myriad controversial issues in which there are likely to be passionate differences of opinion and may therefore be taken as a litmus test of the party's political mood.

The event will consider a pre-manifesto strategy paper that examines the extent to which the party should enthusiastically own the decisions made by the coalition, rather than highlighting the extent to which the Lib Dems were unable to get their way as the minority party alongside the Tories. The strategy paper, with a foreword by Clegg, insists the party was right to join the coalition and lists some of Conservative plans it has blocked.

Clegg's aides argue that the party cannot sensibly advertise the virtues of coalition politics to the electorate if the party is excessively critical of the party's achievements between 2010 and 2015.

They believe he is in a strong position to press members to accept that its strategic future lies in the centre ground, even though polls show Lib Dem supporters would prefer a coalition with Labour rather than the Conservatives by a margin of two to one.

On Trident, the motion to conference is expected to call for the party to back the replacement of the current four Trident nuclear submarines with two or three submarines, depending on whether it is possible to construct a new class of dual-use submarine as part of a larger submarine fleet. The idea was explored in this week's Cabinet Office-led review into the replacement for Trident, overseen by the Treasury chief secretary Danny Alexander.

Labour, to the surprise of some Liberal Democrats, has been scathing this week about the Cabinet Office review and has said a continuous at-sea nuclear deterrence is non-negotiable for the party. The shadow defence minister, Kevan Jones, told MPs Labour would only support going down from four to three submarines if changes in technology make the nuclear submarines more reliable.

The former armed forces minister Sir Nick Harvey was scathing about the Labour-Tory consensus in the Commons on Thursday, saying: "Just getting so many dinosaurs in one place at one time does not mean the dinosaurs will live for ever".The conference will also see a clash over nuclear power with a paper on climate change giving a straight choice between continued opposition to any new nuclear power stations and the coalition position of allowing new nuclear as long as it does not require any state subsidy. The conference voted to oppose new nuclear power in 2009, so the energy secretary Ed Davey has a challenge to persuade the party to adopt a more flexible approach.

He is likely to argue that his still to be completed negotiations over strike price with EDF the French nuclear company due to invest in new nuclear stations at Hinkley Point show he will not roll over and agree a price that amounts to a subsidy.

Davey will be hoping that the green movement in his party, faced by the threat of climate change, recognises that one more generation of nuclear stations are necessary before it can be replaced by renewable technology.

The conference will examine a paper on higher education that includes a de facto endorsement of the coalition's decision to treble tuition fees as a way of injecting cash into university sector. The Lib Dem conference has not formally accepted the coalition decision.

Clegg last week published an economic motion for the conference that endorses the existing economic strategy, but calls for fresh measures to help 16- to 24-year-olds; allow councils to pool borrowing limits to increase house building; expand the British business bank; increase RBS lending to businesses; and making the Green Investment Bank fully independent. It also says the government should explore allowing councils to borrow more without the cost appearing in public borrowing statistics.

The Social Liberal Forum pressure group this week questioned the motion's approach, saying the party must not be seen to be endorsing chancellor George Osborne's fiscal policy, which it described as a compromise "made for the purposes of this coalition," It states: "The only party going into that election defending Osbornomics should be the Conservative party". It is not yet clear whether an amendment will be tabled to the motion