Different driving instructors have different opinions on this one but I say DEFINITELY!
You take mock GCSE's, mock A levels and if you did instrument gradings you'd practice those as much as you could as well, right? Why not with your driving test?
I fully understand why some driving instructors, with other driving schools, say you shouldn't do mock tests. And thats because you should be good enough at driving, after your driving lessons, to pass anywhere, any time and under any conditions. But in my opinion the reality of the driving test just isn't like that! It puts you under so much pressure and requires you to drive so perfectly, that a run through a couple of times with a driving instructor, can really put your mind at ease, take the pressure of the situation off your shoulders and make the driving test process a lot more enjoyable and easier to go through.
Another reason why mock tests can help is that you'll get the opportunity to drive around the driving test area you'll be in for the real test, and if there's a situation that will come up that you misjudge or get wrong through poor judgment, feeling overwhelmed, or just a really tricky bit of road thats difficult to ace the first time you drive on it, like Lombard roundabout in Croydon or Rose Hill in Morden, then doing it with a driving instructor first will be beneficial for so many reasons! Mainly, failing your driving test really sucks, and you don't want to make your driving test into a really expensive driving lesson, just because of poor preparation!
Just coz I'm super nice I've gone around a few test areas that I use a lot with my students and recorded some driving tests on our Youtube channel! I'll take you through a real driving test and talk you through what you need to do where, and the tricky bits to look out for! Check out the one I did in Morden here! And if there are any others you specifically want then let me know and I'll get cracking on some more Youtube driving videos to help you out too!