Help with brushing up on academic skills...

I havent been in education for nearly 10 years and have enrolled as a mature student on an Access to Health course in the hope I will get into university September 2020.

Handed the first assignment set in and as usual did the leaving it till the last minute thing which ended up me rushing to complete it and probably not done all that well (I don't get the grades back for another two weeks) however have realised I massively need to up my game in terms of assignments (I find this hard as I am not the brightest and have found it difficult to get back into the swing of things with learning how to write in the third person, I have no idea how to reference just yet)

What tips can you give me on how to strengthen these skills and really put the hard work in (I know hard work can only come from myself) but I did not stay to do A-Levels and have no idea what is usually expected in assignments (I didn't know an introduction is usually expected along with a conclusion)..

Anyone have any tips and advice for getting these skills and knowledge back? I feel as though at the moment I will not get into university if I don't learn these skills and fast...

Thank you