I believe your first claim doesn’t affect the premiums, but if you change insurance company on renewal (or tend to cancel and renew with M&S as most of us do to get a cheaper policy) then you will have to declare the claim and this will undoubtedly increase the price.
On the claim side, if you think the crack was the result of a particular incident/crash then as far as I can see, you are covered. But if they interpret the claim as wear and tear that has developed over time, by my understanding of the T&C’s they could say its not covered. Otherwise people would start claiming for new roofs as the 100 year old slates are breaking up 🙂
Edit: Beat me to it Ivan 🙂