Well you have strong results on the Access course so I imagine you will be fine. I can't comment on the workload for that course specifically and workload does seems to vary so much depending on the subject. I'm doing computer science and I would say my first year modules were petty easy and not really a step up from Access in difficulty, just more volume. Things do go up a notch in the second year modules but really it is just building on year one.
I wouldn't recommend trying to work 30 hours and study a 'difficult' subject like Biology...... maybe some of the artsy subjects it would be doable but for sciences you will have a fair amount of mandatory lab sessions and it isn't as easy (or even possible) to catch up at home.
As for lectures......well you may well sit there staring blankly, but you wont be alone! My guess is 95% of the class do not take more than 20% of the lecture in. The average attention span appears to be about 20 mins and then you will see people using facebook on their laptop, playing with their phone, generally fidgeting, etc. A voice recorder is a decent investment if you have concerns about your ability to take on board lectures....... that way you can relax knowing everything is being recorded and you can review it later.
Good luck.