Good IT skills and fast/accurate typing when taking dictation makes you an attractive candidate. You need to be kind and reassuring in your manner, meticulous when cleaning/tidying and robust in stressful situations (it's not about you, it's about the patient). Emphasise that you are strong, reliable and hardworking. 31 is an ideal age ... the average school-leaver will take fright when they face difficulties.
Nurses with the National Diploma in Dental Nursing from one of the dental hospitals are the most sought after. Applications open Mar-July for a September start, hopefully this will be the same in 2021. Similar to an apprenticeship, you are paid as you learn.
You could buy a Levison's textbook and learn your anatomy, physiology and charting. The terminology seems difficult at first so it's good to get a head start. Having your Hep B immunisations is an advantage. (If your GP practice is reluctant inform them you are shortly starting work as a dental nurse and need it in case of sharps injuries. They don't need to know that you don't yet have an employer). Having a CPR certificate is an advantage. It is an advantage if in your existing job you are: aware of GDPR rules, named first-aider, named fire-warden or in charge of the COSHH folder (usually found in the cleaner's cupboard). Perhaps enquire locally for receptionist vacancies: as you wish to become a dental nurse they will be more inclined to devote the time into training you on their software. If they use Software of Excellence the Youtube EXACT Knowledge Hub is very useful.
Good luck!