The current version of the Tesco Hudl seems to have a problem with the screen freezing. I know of two Hudls that have had this problem.
Below is a link to a Which? web page that gives instructions as to how to apply a patch/upgrade and how to then calibrate the screen to hopefully prevent the problem.
How to download and apply the Tesco Hudl screen fix
(Since applying the patch about three weeks ago neither of the Hudls has frozen. Time will tell if this has really cured the problem.)