Can someone check if these sentences are grammatically correct?

Thank you very much in advance.

1) I never have my cat washed. I wash it myself.
2) I take my cat to the vet once a year to have it examined.
3) The teacher told his students to open their books at page 30.
4) The man, whose dog was found, offered me a reward.
5) I don't think I'll have my car repaired. I'm going to buy a new one.
6) If I hadn't trained a lot, I wouldn't have been awarded the first prize/I wouldn't have won the first prize (?)
7) They hadn't been waiting for a long time when (by the time?) the concert started.
8) It's going to snow. The weather forecast said the weather might have changed.
9 If I had the possibility (chance), I'd go to live abroad.
10) The emails are being sent now. I hope you'll all get/receive them.
11) St. Paul's cathedral was restored by a famous architect.
12) Have you ever tried my carrot cake?
I've just taken it out of the oven.
13) My granny doesn't let me go out in the evening but she allows me to watch TV till/until late.
14) I've been sitting all day long. I need to go for a walk now.
15) I've been to the hairdresser's (at the hairdresser's is a mistake?)

9. If I had the chance. (Possibility is not a good choice here.)

Your other options are all correct.

15. Either to or at the hairdresser's are correct.