It's similar to what you can expect from CTC or BC - it's basically legal cover for you and your family, but at £24 it isn't bad for the lot.
All this free this that really isn't free as it goes on your claim value should you have an accident, but it does mean you aren't paying out first - as someone who is covered by BC, I had to fork out £3000 in repairs to me and my bike (me costing most of that figure) before I finally got it all back (some 3 years later).