Make your way to Sadlers Mill and follow the map from there. Take the footpath away from the river, between the mill and the first house, then turn immediately right and head off through the fields.
There are some narrow stretches of path, but social distancing is achievable by stepping off to the side.
Although there is really only one right of way through Squab Wood, there are some unofficial paths that allow one to avoid others.
When you come out of the wood, turn right and take the footpath through Roke Manor.