We booked two excursions. The first was with a small group to Stonehenge, Glastonbury and Winchester. We liked it but due to the long distance the time resting in Stonehenge or Glastonbury was rather short. I would recommend to cancel Winchester and give more time in Glastonbury. The second excursion was Harry Potter Studios and Oxford. 3.5 hours for HP is good but could be longer. Oxford was interesting but time was to short to make more than the one hour guide tour and a bit of shopping. I would suggest to extend the time in the studios and combine the excursion with an attraction in London itself (f.e. British Museum).