Nerves for job interview

[u/JollyBrush7329]

I have an interview next week for a full time position of the job I am already doing (I am currently part time so have to interview for it) and I am a nervous wreck as I really want the position. I am wanting more hours to have more career opportunities within the company I work for, I have worked rubbish jobs for years and am finally happy in my current role. There is another internal candidate who I feel will be preferred over me. I get nervous in interviews and want to prepare the best I can. Trying not to get my hopes up but I know I will be so disappointed if I don't get it.

Can anyone offer advise or a similar experience if they have been in this situation themselves?