I wouldn't have thought being Dislexic would specifically be a block to becoming a driver and from what I can recall, most of the tests are verbally briefed and don't require much writing.
You may, however, find the course challenging as that definitely involves a lot of reading and writing both in the classroom and at home. I would compare the workload to an A level in 3 months with a 9 or so hr exam at the end of it (at least that's what it was like with EMT). That said, allowance was made for anyone whose writing wasn't their strong point by giving them more time in the exam.
You can be sure however, that your day to day duties as a driver will definitely require you to be able to read and understand instructions clearly and unambiguously as a matter of safety.
If you're already in a good job then think long and hard about moving across, but if you feel that you could go back easily enough and therefore have nothing to lose, then give it a try. You may find you're a natural, but if you struggle, what you can be sure of is that the training system will stop you at some point, long before you are 'let loose' on your own.