If you have access to a tablet, Teach your Monster to Read is also free and very good. My reluctant reader loves it as it's very much like a game but does help with phonics learning.
Remember that the work being sent home will not be differentiated so the teachers are catering for all levels - my 5 year old is very much towards the bottom end of the reading and writing scale too.
If funds are available, I bought some phonics book packs from scholastic online at the right level for my son and they arrived very quickly.
Twinkl also has lots of resources you can print out - worksheets etc to help practice letter formation and basic maths. The website is slightly tricky to navigate but they've created a home learning and parents hub which is a good start.
Numberblocks and Alphablocks on bbc iPlayer are also a great idea for helping him learn by osmosis!
Most of all don't worry - do what you can but don't stress. When you do have quality time, spend it doing enjoyable things - Lego, baking, playing games together.
My son really enjoyed helping sort washing the other day - long may it continue! 😄