Can i apply for spring weeks/insight days or penultimate internships?

You can apply of course, but without a projected minimum of 2:1 it will be difficult for you to get through the first stages.

If you are at your second year of a 3 year degree you should apply for summer internships and if you are a second year of a 4 year degree then apply to Spring weeks. But as I said, the grades could very well be a deal breaker. In your case I would aim to network as much as possible with professionals from these institutions and try to get your name in there somehow. You could always try emailing a bunch or attending networking events/ workshops.