As you say you're only slightly dyslexic so probably not, but an ability to read and assimilate the written word and carry out basic maths on the back of a fag packet at short notice is apparently a necessity. you'll have to judge yourself wether you're capable unless the RCB has already passed you in which case you're probably fine. If in doubt, bluff it or speak to your careers adviser.
my brother is also dyslexic and in his younger days was a huge fan of a band called Slipknot...
...being the little shoite he was he thought it was cool to dedicate some graffiti to his fave band and his creation is still there on a wall in town...although no-one can work out who the feck 'SilpKnit' are
Shouldn't be a problem fella. Good friend of mine is really dyslexic, but has done a degree, is a WO and is waiting for his LE commission results whilst doing a masters degree is psychology. It'll only hold you back if you let it. Go to an AEC and see the basic skills tutor. They'll help out and develop coping strategies with you.