the 1 off fee isn't substantial enough for 2 main reasons

1-a higher amount would cause the government to put more research and development to make sure side-effect related ingredients aren't included in future vaccines and only vitally essential vaccines are pushed

2-vaccines can lead to a seizures & convulsions, brain damage , deafness etc , leading to extra care requirements and 24/7 supervision and costly medications to boot, a lower quality of life for the carer family

https://www.gov.uk/vaccine-damage-payment