Find out asap what the reading list is for the courses you are delivering. You need to get hold of 1-2 key textbooks that will be the mainstay of your teaching. Look for webites - some may be subscription type sites - that have course teaching materials ready to go.
There must be some teaching materials already around if these courses have been taght by the college.
Get a free download program such as Hot potatoes (from Half Baked Software - honestly) and use it to make interactive units that you can stack up and let students work through at their own pace.
In the circumstances you are presented with, you can only effectively be the facilitator of the learning, so try to arrange your teaching provision so that students are looking into key resources and key websites to find answers to broad questions / problems.
And yes, many of these access-type courses are frankly half-a*sed