Ukip leader will accuse Labour of failing to represent people for which it was founded, and unveil plan for fairer tax system

Nigel Farage will launch a “full-frontal assault” on Labour in Ed Miliband’s backyard on Friday, claiming the party has failed to represent the people for which it was founded.

At Ukip’s conference at Doncaster racecourse, Farage will target the blue-collar voters who have supported Labour for generations as Ukip makes a play for the seat of the late Labour MP Jim Dobbin in Heywood and Middleton.

Labour, whose leader Miliband is MP for Doncaster North, has launched its first major attack on Ukip, painting it as “more Tory than the Tories” and the party of extreme tax cuts for millionaires and plans to make people pay to see their GPs.

But Farage will brush off the criticism by saying Ukip would protect the NHS from abuse, keep it free at the “point of access” and improve the most essential services.

He will unveil plans for what the party describes as a “simpler, fairer tax system” that it says would ease the burden for those on the lowest wages, and proposals to take care of servicemen and women returning from military duty overseas.

Farage will hope the conference passes off with less drama than last year, when he sacked the then MEP Godfrey Bloom after he overshadowed the event with a sexist joke.

Some of the colourful fringe events available at the conference include meetings about “how to tear chunks out of Labour”, an address by two Christian B&B owners sued for banning a gay couple from staying overnight, and a session on the case for independence in South Yemen.

In a hint that Ukip is seeking to exploit the South Yorkshire child abuse scandal, in which girls were groomed by men mostly of Asian descent, the party said it would direct an attack on “Labour-led councils who have badly neglected those most vulnerable by stripping away protections in favour of dodging taboo”.

The party is growing in strength after topping the European elections and winning a swath of council seats. It is particularly strong in southern coastal areas such as South Thanet, where Farage is standing next year, and Clacton-on-Sea, where Tory defector Douglas Carswell is expected to win a byelection this month.

There is speculation that Ukip could announce more Conservative defectors at its conference, potentially such as Chris Kelly or Brian Binley.

Labour insiders are increasingly worried about the threat of Ukip in areas of the north, particularly Heywood and Middleton, where the party has been out in force in recent weeks while Westminster MPs have been concentrating on winning the Scottish referendum.