It is entirely possible to get distinctions if you are organised and persistent.
Working 3 days a week is likely not to exceed 30 hours per week in actual work time. Use your lunch breaks and commuting time to read or review material. Once you know when assignments are due, schedule any holiday time from work you have to give yourself some dedicated study time, a day off a week before a deadline is a good idea. You will typically have less than 21 hours a week of contact time in college. So you have plenty of time on paper to spend doing the additional study and allow yourself time off. Consider getting up early before college and reading material relevant to the classes you are attending that day. You will get far more out of a class you are prepared for. Being confident to ask questions in class will also help. Try to have assignments complete a few days before the deadline. Submitting at the last minute adds to stress and if something comes up at the last minute, you may miss your deadline.
Prepare yourself over the summer for the English and Maths elements of the course, if hou are confident in this area, you may be able to use the time allocated to these subjects more effectively. You should be able to borrow books from the library which cover the GCSE material, the Access course equivalent will be at a similar level.
If you have previously prioritised socialising over studying, this will need to change for the duration of your Access course if you want to achieve your goals. The teaching part of Access is only about 7 months, once you take Christmas and Easter into account. So ask your friends and family to support your studies by being understanding when scheduling meet ups etc. But do your part by being organised about your studies and if you need help, ask early, don't suffer in silence.
When I had to work and study at the same time, being organised was key and resisting the urge to procrastinate, made for a positive study experience. Even when I could study exclusively, unless you are organised, time has a nasty habit of slipping away. The only difference is you don't have work as an excuse for not getting it done.
Good Luck.