I studied Acess to HE, Chemistry & Biology two years ago to gain a place on a Vet Nursing degree. I had a stupidly easy offer of 1 module at Distinction in biology (by the time the offer came through, I already had two). However I really struggled with the Access course. Chemistry was not my strong point and I lost count of the tears in the library the day before the exams and wrecking my head with assignments which I didn't understand. I was working 40 hours alongside this at the time on night shifts so I had plenty of time (paid by work lol) to revise and get assignments done. Fast forward two years and I'm starting a chemistry degree. Lets say I enjoyed the challenge. It all depends on who you are, what your weaknesses are, and how much you want to achieve. I ended up coming out with 42 credits at distinction and 18 at merit, with distinctions in all bar one of my chemistry modules when I really thought biology would be my strong point. If its still the same as when I did it, 9 credits were available in modules such as Reflective Practice, Research and another pretty pointless but compulsory module.
We also go first and second drafts, however with exams we learnt the trick that if you checked the assessment criteria on the front cover of the exam it usually gave you a clue as to the answer, this worked in biology but not in chemistry so if you do get completely stuck thats at least a starting point. Good luck!