Depends what you mean by "independant" and how far up the Thames you want to go.
Two independants are Mid-Thames just below Caversham Lock and there's another one by Tilehurst (end of Scours Lane). Both could lift you and do repairs.
So could loads of others (Val Wyatt - ??- and the one just below Shiplake) but you've said independant so guess you're not looking for anything in a chain such as MDL???