The first large-scale fracking in Britain has moved a step closer after an energy firm said it had completed drilling the UK’s first horizontal well at a site in Lancashire.

Cuadrilla said the development was a “major milestone” towards the first shale gas exploration in the UK since 2011, when work was halted after it triggered a minor earthquake. The company said it hoped to begin fracking at its site on Preston New Road, near Blackpool, in the summer, pending government approval.

Cuadrilla has reported signs of a “sizeable quantity of shale gas” on the site and said its tests suggested each well could extract enough gas to power 5,000 homes for 30 years.

The drilling announcement was met with scorn from environmentalists and protesters, however, about 200 of whom were outside the gates of the fracking site on Tuesday.

Doug Parr, the chief scientist for Greenpeace UK, said: “Just as Bloomberg reveal that solar plants have dropped in cost by 20% in the last 12 months, Cuadrilla announces that seven years after the last UK well was fracked, they are almost ready to have another go, notwithstanding local opposition, pending government permission, sometime in the summer, maybe.

“And this announcement of yet another delay in getting started is what Cuadrilla are trying to pass off as a success.”

Cuadrilla said the well had been constructed about 2,700 metres below ground and it ran 800 metres through its shale gas reservoir. The company said it would now begin drilling a second well and had planning permission for a total of four wells on the site.

Francis Egan, Cuadrilla’s chief executive, said: “Our completion of the UK’s first ever horizontal shale gas well is a major milestone towards getting Lancashire gas flowing into Lancashire homes as we lead the way on UK exploration.

“From the data we have amassed so far we are optimistic that, after fracturing the shale rock, natural gas will flow into this horizontal well in commercially viable quantities demonstrating that the UK’s huge shale gas resources can be safely produced and contribute to improving the UK’s energy security.”

The announcement coincided with the start of three months of protests at the site, beginning with a women’s week to mark 100 years since some women won the right to vote. Some protesters wore suffragette sashes and chanted to the beat of a samba band as they prepared to take “non-violent direct action” against trucks attempting to enter the site on Tuesday.

Claire Stephenson, from the group Frack Free Lancashire, said protesters were “surprised and concerned” the company had “only just managed” to complete the horizontal well.

“According to their information, this must put them almost a year behind their schedule, which considering their enthusiasm for erosion of democracy and land, makes their announcement a bit of a damp squib,” she said. “We have today begun a three-month campaign against this industry. We are resolute in our commitment to ending this industry in Lancashire and the UK. As we’ve stated before, we’ll be here until Cuadrilla are not.”

The Preston New Road site was initially refused planning permission by Lancashire county council in 2015 but that decision was overturned by the cabinet minister Sajid Javid.

The government has yet to give final consent for fracking but ministers have repeatedly said they support the development of a shale gas industry.

Tuesday’s announcement means Cuadrilla will almost certainly become the first company to resume fracking in Britain this year. A rival shale gas explorer, Third Energy, had expected to win the race to frack at its site in Kirby Misperston, in North Yorkshire, at the start of the year but that has been delayed until October as the government scrutinises its finances.

The Barclays-backed company has been late in filing its latest annual accounts and its accounts for 2016 showed it made a £3.4m loss and had debts of £55m. The firm needs the green light from the energy secretary, Greg Clark, before it can begin fracking.