Technologist or dosimetrist?

You will need to find a department willing to support you in achieving registration as a Clinical Scientist. Working as a Technologist would not enable you to meet all of the requirements for HCPC registration and you would need to agree a modified Job Description with your line manager that would allow you to achieve the required competencies. This may mean that you would have to be working under supervision in a trainee Clinical Scientist role, although this might be the same pay level as a Technologist.

Relevant experience always counts in job applications so having worked as a technologist might well help you to successfully apply for a position that includes the option to work towards registration, however you would need to meet the requirement to demonstrate educational equivalence at FHEQ Level 7.