My son also found the NVR questions harder than expected. As you have mentioned the VR test is on Tuesday. Hope this is of same format as Nfer (85 questions, 50 minutes) and no special tricks fitted-in for the Tiffin schools.
BTW, it was me who got drenched in the rain while waiting to collect him after the test!!
For verbal reasoning I have bought practice papers from Nfer, Bond, AFN, Athey, 1 paper from The Tutors and one more publisher PLUS all possible freely available papres from the known publishers PLUS couple of books from local library.
Mike Edwards from The Tutors had contributed the possible words used in Nfer questions on this site's freely downloadable section http://www.elevenplusexams.co.uk/revisi ... wnload.php
Here you can also find few revision questions as well.
A while ago I downloaded a document on 'Verbal reasoning explained' from Athey. This has tips for 40 types of VR questions. I cann't find the link anywhere. But I can mail you the document if you want.
Good luck with the preparation. If you heard from anyone regarding the past years VR tests at Tiffin schools please let me know.