When I was in the first few weeks hubby came with me on some of my "runs. He quick march walked along side me and kept up the whole time! It doesn't matter how fast/slow you go as long as its more effort than walking. Thats what counts at this stage and thats what will make you fitter and stronger to get faster eventually.
Reading a lot of the posts I think people put too much pressure on themselves for speed and distance. Just aim to finish the programme. Ignore the 5k bit, thats just a guide. I took just over 40 minutes to complete my first 5k. I have done almost 10 of them since and am still only doing them in 33 minutes!
When I did the programme I was very scared at moving on each week. I thought I was going to die! But I tried it each week and each week I found that I just 'could' do the runs. It was hard work, sometimes I felt sick or had knee pain or ankle pain or just plain didn't want to do it but I made myself and was really dead chuffed when I finished each run.
As for the dizziness, did you eat enough or drink enough water before your run?
Keep it going. It's the best feeling in the world to finish it.