It is legally your duty to educate your child from the term after they are five.
This could mean at school or at home.
If you defer applying for a place until they are five, you will almost certainly be told that they will have to go straight into year one, missing reception - going into reception a year late is in most cases, just not an option. (I have looked into this in the past year or two - Ds1 now in reception but part time).
You will also be told that you might well not even be give a place in year one, as most of those places will be taken by the reception children already there.
In other words any deferral is taken quite badly by many LEAs in England. They do not encourage it.
Your best option is probably to opt for home education until you are happy for your child to begin school.
Good luck, there are many of us who agree reception age children are just too little!
(Ds enjoys it p/t, because he loves seeing - rather, hitting - his little friends, and some of the curriculum - mostly the singing etc. but f/t though being hinted strongly at by the school, is beyond his physical capabilities imo)