Cycling from John O’Groats to Land’s End is a big enough challenge for most of us.

But three ex-servicemen, including veteran Royal Engineer Steve Craddock from Chatham, will be going the extra mile - or nearly 500 miles more.

Steve, 59, who will be joining retired Royal Marine Brian Kilgannon and ex Navy able seaman Lee Patmore, will be topping up the 960-mile journey by visiting seven military bases along the way.

The trek will be made all the more arduous because Lee suffers from fibromyalgia, a painful and debilitating illness and is now mainly confined to a wheelchair.

Steve and Brian have post traumatic distress disorder and will be fighting their own mental demons along with with the physical toll the route will take.

Steve,a dad, who lives in St Mary’s Island, has completed numerous gruelling tasks and raised an amazing £350,000 for the Help for Heroes charity now in its 10th year.

The former sapper, who served 15 years and went on six operational duties of peacekeeping duties, including Northern Ireland, is aiming to raise at least £20,000 for H4H and mental health charities.

He said: “This will be a tough one, but we will gain inspiration from Lee who will be in pain and discomfort all the time. He will not know from one day to the next how is body is going to cope.But we shall carry him if we have to

Lee, who is in his 40s and is a fitness instructor at a leisure centre in Essex,will take on the epic ride in a custom-made bike he will power with his arms.

VIDEO: Steve Craddock is going the extra mile for Help for Heroes

The trio will set off, on Cycle 2 Recovery, from John ‘O Groats on bank holiday Monday, May 1 and hope to complete the course in 30 days, covering between 60 to 70 miles a day.

Among the stop-offs will be Tedworth House in Wiltshire, a rehabilitation centre for servicemen with physical and mental health issues.

They will also pay a visit to a war memorial in Newcastle in memory of a colleague of Steve’s who was killed in Ulster.

He said: “This is a lot about hidden mental wounds. We have said £20,000, but let’s make it more like £50,000.”

Steve, whose tireless efforts have been recognised in a community award presented by former Prime Minister David Cameron, is involved in raising money at Medway’s Armed Forces Day in June.

Last year he organised a 100k Cycle 4 Heroes ride around Kent raising a total of £10,000.