Sir Ian will walk around 160 miles in and around cities across Britain over the next 10 days, starting in Glasgow on Thursday, He will start in stopping off at 10 locations and finishing at Ham House, London on April 21.
Throughout the "Great British Walk", which will raise money for blood cancer charity Leukaemia & Lymphoma Research, he will be joined by young patients who are either being treated for the disease or are in remission.
Around 30,000 people are diagnosed with blood cancer such as leukaemia, lymphoma and myeloma in the UK every year.
In 1985 only 20% of children survived the most common form of childhood leukaemiam, now more than 90 oer cent survive the disease, according to Leukaemia & Lymphoma Research.
Sir Ian, the charity's president, said: "I need people to sign up and join me on the walk and help ensure that every child diagnosed with blood cancers, including leukaemia and lymphoma, survives. I won't stop until we beat childhood blood cancer, but I can't do it without you."
You can support Beefy's Great British Walk at justgiving.com/beefywalk2012