I get a horrible tingly, tickly feeling in my legs in bed or evenings when sitting down which can be relieved by moving a lot what could be causing this?

Multiple causes. Typically, tingling feet at rest can be caused by multiple causes. Many of them are benign (such as pressure on the nerve at the edge of the chair/couch). Others are less benign and may involve moderate to severe lower back arthritic or degeneration. The exact nature will of your symptoms will require a detailed history and exam by your physician.
Restless Leg Syndrom. Relief can be provided by Dopamine agonists.