Unbelievable – that is the word Charlie Austin uses time and again to describe the remarkable journey that has taken him from being a part-time footballer in the Wessex League to a prolific goalscorer in League One in the blink of an eye. Anybody feeling disillusioned with the game and resentful of the Baby Bentley brigade, and their telephone-number salaries, should spend some time with Austin.

Six months ago Austin was laying bricks for a living and scoring goals for Poole Town. As recently as mid-September he was turning out for Poole, banging in five goals away to the Portsmouth side Moneyfields in his final Wessex League appearance, in front of a crowd of 88. Now he is playing six levels higher for Swindon Town, yet Austin has scored 13 goals in 18 starts since making his full debut against Carlisle in November when, in a sign of things to come, he scored after only three minutes.

Life has been spent in the fast lane ever since. The nine-month contract signed in October, after a fee worth up to £50,000 was agreed with Poole, has been replaced with an improved two and a half-year deal, allowing Austin to trade in his Vauxhall Corsa for a new Audi A3 last week. On the pitch his performances are continuing to catch the eye, with Stuart Pearce, the England Under-21 coach, joining a growing band of admirers.

Austin, 20, still seems to be in a state of shock as he puffs out his cheeks and tries to take in everything that has gone on since he put down his hard hat and trowel for the last time. "People ask me: 'Can you explain how you have done it?' But I can't explain it," he says. "I can explain what I'm feeling but I can't explain what has happened. To come from where I have been, to now talk of England ... what can you say? It's unbelievable."

The first time Austin knew his life had changed was when he was about to make his league debut, at Norwich City in October. "I went for a warm-up and got called back and the fans started singing my name when I was sat on the bench," he recalls. "I thought: 'Oh my god. There are 25,000 people in the ground and there are around 1,000 Swindon fans singing a 20-year-old's name that has just been working on a building site.'"

Austin admits that he thought his chance to become a footballer had gone when he started labouring for his father's building firm after leaving school. Reading had rejected him when he was 14 and a knee injury ended hopes of a move to Swindon shortly afterwards. He eventually joined his hometown club, the Berkshire side Hungerford Town, who are at a similar level to Poole, and played Sunday morning football with his friends, getting changed in dressing rooms "where you could hear the other side's team-talk".

At that point, Austin says he had "found Friday nights and was drifting downhill", but when his family relocated to Bournemouth in 2008 it proved to be the turning point. He signed for Poole, fell in love with football again and scored 46 goals in as many games, attracting interest from Bournemouth. Austin spent eight weeks training with the Cherries in the summer but the League Two club were unable to sign him because of their transfer embargo and Swindon jumped in.

Having scored for the Wiltshire club's reserves, Austin returned to play for Poole a few days later, when Danny Wilson, Swindon's manager, came to watch. "I don't know what he expected in terms of Poole Town's level," Austin says. "And I don't think he knew I had to work on the day of the game, not finishing bricklaying until 4.30pm, before driving an hour from Basingstoke, where I was working, to get to the match. But I scored two in the first half and he left at half-time."

Two days later Wilson rang up and said he wanted to sign him. Austin, overcome with emotion, called his father, Fred, straight away. "He always told me never to give up because you never know who's watching," says the Swindon-born striker, whose parents and grandfather travel everywhere to see him play. "I try to see them in the crowd but it's a lot harder now than what it was when I was at Poole."

There are also a few other subtle differences he has had to come to terms with since becoming a professional footballer. "People ask me for autographs now and I think to myself: 'Are you sure?'" Austin seems genuinely bemused that anyone would be interested. "And I've gone from Poole Town where I took my own kit and boots, still clogged in mud from the game before, to having someone cleaning my boots for me and all my kit being laid out. It's unbelievable."

Swindon fans may use that word to describe his impact at the County Ground but, rather amusingly, Austin thought he would be dropped when he failed to score for the first time in four matches. "I thought the fairytale was finished. I beat myself up because I thought I had to score every game because I was used to doing that for Poole Town. But I played in the next game, against Brighton, and scored again. My life had changed from being a bricklayer to a regular goalscorer in League One."

The challenge for Austin now, like others plucked from non-League, is to remember where he has come from. Not that you imagine it will be a problem. "One day, when I was 17, I was working in a place called Overton," he recalls. "By 2pm we were drenched through and it felt like I had a glass back. I couldn't bend it and I was covered in mud. If I ever get fed up for one minute with football, I'll think back to that day and remember I've got the best life in the world now."