hi, i am considering taking an entry qualification

hi, i am considering taking an entry qualification in refrigeration and air conditioning this coming September . If I am to explain my background then you will be able to inform me.

I have not been in school or college for 7 years, I worked in retail at the check outs since I left school. I suffer from minor memory problems. I am 25 yrs old and didn’t come out of school with the best GCSEs and have a Intermediate GNVQ in building. I am worried that the 6127 City and guilds refrigeration and air conditioning or equivalent entry qualification might a bit challenging for me.

I have found a book at my local library even though it is a bit advanced for what I will be studying I have learnt 1 or 2 things that I find interesting. However my main concern is that this course will be a bit too challenging for me, is there a book that I can get that will give me a good idea at what I will be studying and at level 2 do I need to memorise Refrigerant numbers replacing older ones and at what detail? Would I need to learn Refrigerants ODP, GWP, Saturation temp, Condition temp. What about lubricants and their compatibility with refrigerants?