If it is actuator only needed, then the TAM4 is a direct replacement for the TAM2:
https://www.heatingcontrolsonline.co.uk/acl-drayton-invensys-tam4-3-position-actuator-p-113.html
If you have the old "lifestyle" model then no, you will need to replace the whole valve.
If you have the newer ZA6 model, then you can replace just the actuator (grey box).