Result! Enjoy your summer.
The LA is likely to get in touch at some point to ask about your provision. Many LAs like to imply that you must accept a home visit and allow them to meet your child. This is not a legal requirement and home educators generally advise declining this "offer". I would hazard a guess that it would be particularly risky in the case of a child who has just left school due to anxiety. LA staff can be unpredictable and might say something which would worry your son, such as criticising his education, or mentioning that he could be forced to return to school if your education is inadequate (technically true, but inappropriate to mention at this stage, and possibly upsetting to the child).
If they come back to you asking for information about his education, you might promise them a report in a few months' time. Earlier than that is pointless as he won't have done much yet, and you aren't required to have advance plans. By the time that date rolls around he will be back in school anyway. Or if you've changed your mind and kept him out of school after all, you will be in a good position to write up a brief report on his home education.
You don't have to do any formal work with him and there are no required subjects. Since it isn't long until his secondary start, you could just let him learn about whatever interests him while he recovers from his difficult time at primary. It would be useful to observe him and see how he learns best: does he like to discuss things or think about them quietly, does he like to concentrate on one subect at a time or switch between several, what interests him most, does he grasp fractions, how fluently can he read. All of this will become apparent to you over time without making him sit any tests, just by noticing how he approaches daily life. If he goes to secondary then you can provide this information to them, or if not then you can use it in deciding how to educate him at home.
Have fun!