Protesters planning to demonstrate along the route of Lady Thatcher's funeral procession have been given the go-ahead by police to turn their backs on the former prime minister's coffin as it makes its way through central London to St Paul's.

Scotland Yard has repeatedly asked people planning demonstrations to let them know in advance, warning that anyone causing "harassment, alarm or distress" could be arrested under section 5 of the Public Order Act.

But Rebecca Lush Blum, 41, from Hampshire, who has set up a Facebook event calling on people to turn their back on the funeral procession, said she had spoken to the police and had been reassured that her protest could go ahead near the Royal Courts of Justice.

The prospect of high-profile protests being beamed around the world during Wednesday's funeral has raised concern among some senior Tories. Lord Tebbit, the former Conservative chairman, described the protesters as "mindless bigots" but said that, provided they were obeying the law, the police had no option.

"I think they ought to be grateful for the fact that the people who hold our views, and who are not mindless bigots, won't allow their behaviour to provoke us into words or behaviour which would could be seen as a breach of the peace."

He added: "Hopefully, those of us who admire Margaret Thatcher are too well-mannered to fall for the bait."

Several Facebook groups have sprung up since Thatcher died, calling on people to demonstrate their objections to her legacy and the scale of Wednesday's funeral, but police refused to say how many other demonstrations had been sanctioned ahead of Wednesday's procession.

Blum wrote to the police and then spoke to an officer involved in security planning for the funeral who reassured her that the Met were happy for her protest to go ahead.

"It is the first time I have ever asked for permission to protest but I am a working mum now and I just can't afford to be kettled or arrested and miss the school pickup. He was very reassuring and we agreed a point near the beginning of the route where I can stage the protest and that I can advertise it."

Blum's Facebook event is one of several urging people to turn their back on the procession, which have attracted hundreds of supporters. One such group, Maggie's Good Riddance Party, plans to hold a "right jolly knees-up" outside St Paul's Cathedral.

"I don't want to upset anyone but I feel very strongly that public money is being used to venerate a deeply controversial politician who caused huge suffering and devastated this country," said Blum. "I don't know how big it will be but I felt like it was an important to let the world know that a lot of people in this country strongly disagreed with what Margaret Thatcher stood for."

The planned funeral protests follow the row over whether the BBC should play Ding Dong! The Witch Is Dead, which was pushed to No 2 in this week's singles chart by anti-Thatcher campaigners. And on Saturday night about 3,000 demonstrators took part in an anti-Thatcher party in Trafalgar Square. The event, which attracted trade unionists, miners and anarchists, passed off without major incident.

There is agreement among most left-wing and anti-capitalist campaigners that the demonstration before the funeral will be smaller than Saturday night's party. However, because of the increasingly bitter divisions over Thatcher's legacy and the number of high-profile figures – including the Queen and prime minister – in attendance, police say it still represents a serious security challenge.

The Met say final judgments about exactly which protests will be allowed will be made on the day, although they have said they do not see their role as enforcing respect for Thatcher's legacy.

Funeral organisers want the public to be able to line the route to pay their respects, but the police acknowledge that this may allow someone to mingle with mourners before attempting to disrupt the procession. The Met said they had a "variety of tactics and powers" at their disposal, adding that they would impose "sterile zones" along on the route where neither the public nor protesters would be permitted.