Wheel Nut:
You are being unrealistic if you think a computer game will help you drive a car, lorry or white van to give you any useful experience, you cant press ctr, alt,delete and unkill yourself.
Perhaps off topic, but when I was a nipper I had a ride-on pedal tractor with a trailer. Used to love riding it around the garden, reversing it into the garage, filling it with muck etc.
I did my CE at 18 and I firmly believe that helped, I’d never used/reversed any ‘real’ trailers before but I had no issue with the exercise - I firmly believe it is thanks to the above.
In answer to your question OP; go for it. We run a driver training school and more often than not the younger drivers absorb things far quicker than the seniors!
Edited to add: 20 hours direct to CE sounds quite tough if you’ve no experience reversing or driving anything large. For the newbies, we are running 6hrs to conquer the 3A (reverse, uncouple/recouple) followed by 21hrs on-the-road training + test. Total around 28hrs. Still early days and still testing the waters like most schools, but for the moment it seems about right.