Have a look at your local university requirements for dental hygiene and therpy. There are multiple pathways onto the course. With your level 3 qualification i think university require x2 post qualifications in dental nursing so these can be radiography, Oh etc.
I wanted to go down a different career path way into adult nursing. I felt for me and my age career oppurtunities would be better, and i had an interest in nursing in an acute hospital. I completed the access course and went to university which is also local to me. The access course is free for under 24s and for over i think it is a £3000 loan which gets wiped off after 40% of the uni course is completed.
As a homeowner the nearest dental hospital was too far for me to communte on the bursary the nhs provide.
Best advice is see how the course goes and complete it. See what career development oppurtunities your company provides. I looked at doing sedation, my company would have paid for the course in exchange for me to work within the company for a yr or 2. My employer would offer additional pay for anyone who would complete a post qualification course if they could use it within the practice. If i did choose to complete the sedation course i would not of been paid any additional pay as there was no dentist qualified in the administration of sedation.
The cost of the course is £1000+ and as i said you would have to complete x2 of these courses.