Yes, get him moved on. This is why I say so...
DS1 had a really hard time with reading in Y1. I never really questioned why, just accepted that he found it a challenge.
Now I realise why... Back at age 5 DS1 was not put up when he should have been and, now I remember was 'jumped up' to a higher stage.
Now I realise it was stage 3 he missed because my DS2 is on stage 3 and I and Ds1 have never seen the books before and we love the series the school uses (Biff and Chip fans are we) and all of the difficulties I remember with reading with DS1 I now see were actually gaps in his knowledge that directly relate to the sounds learned and practiced at stage 3!
DS1 had overcome it, I left him alone to just enjoy reading (after too much pushy and worry before) for all of Y3 and now he is above average, but I and he have talked about these stage 3 books and he has said. 'I wish I could have read them Mum.'
Hope that makes sense, I should have gone to bed already. If the school won't cooperate then you might choose to order in books through the library or purchase on line / ebay if possible, but in any either way if you can avoid learning gaps then that's the best job you can do.
I wish I had know that for my ds's sake. Good Luck