blueroseking - the competition for seconded places (as against direct bursaried entry for pre-registration number) is fierce, and you will have to be able to demonstrate in your application that you are a really strong candidate, and that your becoming a nurse will be a future benefit to your sponsoring organisation.
There should be a page in the application pack where you have to make a personal statement, and this is where you can bring forward your personal qualities and your commitment to the new role, and why you want to become a registered nurse rather than to remain at HCA/Care Assistant level.
I don't know where you work at the moment but in our area, the Trusts only have a limited number of funded secondments each year, so they can afford to be very choosy and many applications can be discarded due to a weak application, without even getting to interview stage at the University. Make a strong confident application, leave nothing out, if they ask for evidence of previous courses attended, send copy certificates etc.
If you get to interview, be smart and businesslike, take your portfolio if you have one, demonstrate that you know what's involved - one of the questions is often about the amount of work involved on any long programme, and how you and your family are preparing so that you have dedicated study time (they are not allowed to discriminate e.g. if you have small children perhaps, but it helps to know that you have thought about this and you will have time to study away from uni too). (Don't be like the person I interviewed once for a nursing course, who brought a plastic carrier full of loose papers with her, and really didn't seem to understand what she might be letting herself in for - be prepared, and show that you are orderly and a good record-keeper!).
I wish you very good luck and - if you are short-listed - a good interview. Let us know how you get on!