There are a few out there and I know there are suggestions in the link. Just wondering which ones you used, I was looking at Drivingtestsuccess.
My preferred is drivingtheory4all
Pete 
I used an excellent app called LGV Theory. When I did my tests there were only one or two questions that hadn’t come up in the app. It has mock tests too, best £10 I spent
I used this drivingtheory4all was really good , I did all my cpc modules using this , has an app you can down load and use as well
Do the theory apps contain the actual questions or just similar ones?
The one I used had identical questions. Out of the 100 there were only a handful I’d never seen before on the app.
I used this one
LGV Theory Test and Hazards by Deep River Development Ltd
I used “Driving Test Success” and it worked for me.
Realised after a few minutes that they re-word the same questions a lot but it worked.