I did an Access course last year at the age of 28, after being out of education for 12 years, and was worried about how I'd cope academically. However, I needn't have worried; the course is specifically structured for 'mature' students as a way of easing them back into education and preparing them for university level study.
I thoroughly enjoyed every aspect of the course, and the support from the tutors and classmates was second to none. As well as gaining the academic qualifications necessary for university entry, you also learn key academic skills such as how to tackle assignments, researching, referencing, time management and portfolio building.
I really don't think you need to 'brush up' on your GCSEs before starting the Access; the tuition is structured so that you are able to study subjects without prior knowledge.
I successfully gained my Access diploma and secured a place at university. I will be commencing my Midwifery degree in May, and I can honestly say I would not be doing that if it were not for the Access course.
I cannot recommend it highly enough, and I'm sure you'd enjoy it. Good luck with the course and with your future career!