Afternoon WoR,
Many different offerings out there, I have been doing a revalidation after 15 years out of the saddle and have been using
www.easypplgroundschool.com which has been pretty good. Have an army of instructors you can contact, and they update the material regularly across all subject so its always current and up to date. Full courses for the PPL and CPL syllabus, question banks and tests etc. You basically pay for a course which lasts 30 days I think (dont quote me on that) and you can dip in and out and do the test at the end. You can even print a certificate off to wave under your instructors nose to show him you are ready to take the real world exam.
Again, ask 10 people this question and possibly get 10 different answers but this worked for me.
Good luck with it all.
Trevelyan