The Decimal Day coin with the Arnold Machin portrait will only be available in an annual set. The £5 coin never circulates. A while back it was reported that there was several year surplus of £2 coins.
I don't think the 75 years since the death of John Baird 50 pence will circulate since I think some of others for 2021 will circulate - the Charles Babbage 50 pence for example.
The Decimal Day coin with the Jody Clark portrait has to be purchased outside of the set.