There is one issue not addressed in answers above is how the stock positions can be relocated with the beneficiaries.
As Trading 212 has no in specie transfer as yet, probably investments will all have to be sold for cash. This is not ideal as my surviving partner would lose out, even if repurchasing the same stocks. I am hoping I live to see the day that in specie transfer becomes possible with Trading 212. Other brokers would be able to transfer the deceased stock directly to any investment accounts of beneficiaries.
When a person dies their spouse receives an additional ISA allowance that year equal to the value of the deceased person’s ISAs, so that amount of money can remain tax sheltered.