I am local to Southampton and I agree with this. Get a car, and you can visit nice little towns like Lymington, Romsey, the New Forest, or go to Winchester and see the Cathedral there as well as some nice museums, a castle, old roman walls etc. There are loads of "National Trust" or "English Heritage" sites nearby which usually have great grounds to walk through, but also historically significant.
Plan appropriately and you will see much, much more by yourself than you would on a tour in the UK.