Kevin McCloud returns to Graven Hill in Oxfordshire, the UK's largest mass self-build site, to witness the trials, setbacks and successes of those who are designing and building their own, highly individual homes. First up are Carlos and Maite, who have ambitious plans to build a bold, Spanish-inspired home. But Maite does not just want to live in it, she is also designing it - without any professional qualifications. Meanwhile, co-presenter Natalie Huq follows the birth of a new street in Glasgow, where the local council have given six families an opportunity to construct their own homes on a small plot - beginning with an American-style ranch.

Prabhjot and Shalini's new-build is a super-quick kit house which should go up in a matter of weeks. But with such a close community, their home will need to take their friends' tastes into account as well as their own.

Kevin meets Joanna and Ben, who are channelling all their ingenuity to realise their vision of building an American ranch-style house in a gritty part of Glasgow on a tight budget.

Kevin McCloud follows the progress of Army couple Leah and Craig, whose lives have been dictated by the military. They have designed a contemporary, timber-clad kit house where they can escape from the beige of the barracks. Kevin also meets Jitinder, who works as a consultant helping businesses operate more efficiently - skills he is using in the process of building his own Hollywood Hills-style bachelor pad.

Tim plans to move from his small flat in Bicester into an architecturally daring home at the UK's largest mass self-build site in Graven Hill. With the help of his dad Michael, the project is supposed to be a chance to spend quality time together outside of work but the stress begins to ramp up when the five-tonne car lift Tim ordered from China doesn't fit into the specially prepared hole in the basement. Plus, Kevin and Natasha revisit Jitinder, whose house was unfinished due to the moisture problems and his resin floor last time they met, now they experience the full splendour of his Hollywood Hills style home.

Kevin and Natasha meet couple Jane and Richard who are building houses three doors down from each other in hopes of providing a new life for the five children they have between them. But where Jane's plan involves a beautifully crafted home with a high-end kitchen, Richard is planning on building a minimal and sleek property with some special architectural moments.

At Graven Hill, Tom and Lori hope to hit the ground running with their self-build adventure of a lifetime. But it quickly turns into a nightmare they could never have imagined.

Jonathan uses a new experimental system that uses wooden boxes held together with only bolts to build his home in York. With a plan to build three storeys, it will be the largest structure ever made using this method.

In Glasgow, we catch up with Amanda and Chris, who turned their cramped house into a fab family home, and Joanna and Ben, who built a Wild West-inspired abode on the same street.

Kevin McCloud follows John and Julia, who are realising their 30-year dream of building an amazing house designed by architect John after years of bad luck. They have secured a plot at Graven Hill in Oxfordshire and John has designed a modernist wedge of a home for them to retire to. But as soon as they start, their run of bad luck continues - the lockdown brings construction to a halt and every month in their expensive rented house eats away at their budget - in turn threatening their vision for a comfortable retirement.

Shop owner and jewellery maker Karen builds her version of a mountain hut in central Glasgow, inspired by hikes in the Scottish Highlands. After waiting five-years to get started, the project leaps into action when Karen and her neighbour agree to lay out their foundations together using the same contractor. Retiree William is building an old-style home next door, the pair come across some hurdles building next to each other.

The most senior builders on the street set out to create two unique, bespoke homes. During the construction process, these old friends face serious challenges as their relationship is severely tested

Two young couples make their own homes, getting on the property ladder at last. While one pair scavenge for building materials, the construction effort pushes the other pair close to breaking point.

Paul and Blanka hope to build an ambitious and cheap eco-home. But the project costs the family more than they bargained for - not just financially.

A pair of 20somethings take a risk building their first home together using an untested method. And a father and son hope to bond building a family home with space for all.

A couple of engineers plan an upside-down house. Garrie is building the largest project on the street. The stakes are high though as his wife Sue has health issues.

Kevin McCloud follows the last of the self-build projects, as married couple Pauline and Godfrey seek to downsize to a modular, factory-built home that is erected in just two weeks

In Yorkshire, Nicola gives a traditional redbrick home a modern twist, but will it work? Matt and Maryellen create a Brazilian-inspired home with flamboyant colours, textures and a butterfly roof.