It's tough when you feel under pressure.
Take it out of context - don't worry about the school books. Lots of little, low pressure exposure.
My kids loved alphablocks - it's very simple and episodes are only a couple of minutes long. Available on iplayer.
There's a free online game that mine loved - Teach your monster to read. Lots of little letter recognition games. Again, very short so you don't need to do it long, but with lots of practice and praise.
Magnets on the fridge - get 2sets and do matching games - "find me one the same. Well done! What sound do they make?". Very gradually build it up with 2 letter words e.g. "up", "it", "in", "on". That gets the idea of blending without it being quite as daunting as CVC (although of course if he's doing well you can throw in some of those".
Write it out and get him to say the latter sounds as you write them - some find this less daunting than being presented with a whole word.
Make it tactile - jelly, foam, ice..... Again, focus on matching and sounding - "find me the one that says mmmmm".
Above all, don't stress! Keep these activities totally separate from just reading books to him for fun. That way you don't risk spoiling reading for enjoyment.