Ok so take a deep breath, you have results and you have an offer. Which is great and congratulations!
However, you do now need to decide what is most important to you, and if whatever most matters is important to you, then a year getting there is not a waste. Its just another year, I think you have the following choices:
1. Decide that newcastle is most important, in which case do the retakes. But only focus on 3 as 4 is a waste of energy.
2. Decide that law is what you want and that the insurance place is a good place to study. Inwhich case the foundation year is great for securing that place and an excellent preparation for the degree course. This could feel more of a step forward than resitting and risking the grades don't go up
3. Look around clearing to see what other options you have with the grades you have.
Hope this helps, and that you can begin to see a choice that you like.