Yes, you may have to pay an excess (But probably not much more than paying for carpet cleaners etc). I think we were allowed £1200 for a large lounge sized wool carpet, I chose what I wanted in the shop and the insurance paid them direct. We didn't pay extra for underlay though, but perhaps the carpet I chose was less than the £1200 allowed so the underlay was incuded in that cost. Our premiums did not go up the following year, but yes, you do have to disclose claims if you want to move insurance companies. Wen we looked tor enew this year, we did try another company and admitted the carpet claim, but it did not make a difference to the amount they had already quoted us. Obviously all insurance policies/companies vary by what they will or won't do.
The aftermath of my accidental homebirth shifted with salt. None of the spray cleaners were any good. I soaked the carpet, covered the area with salt, let it dissolve and then stood on layers of kitchen roll to absorb the water + stain. Rubbing it just rubbed the stain further in.
The only thing you have to remember with an insurance claim us you have the excess to pay. Also your premiums will go up the following year if you stay with the same company. If you go with another company they will ask you if you had any claims. It goes against you on any new policy.
I dropped bleach on our 10 year carpet. The bottle fell out of my shopping bag as I carried it in & the lid wasn't on properly. It spilt in my hall way & lounge. We were able to claim. We had to pay for the underlay & excess but got new carpet. We were emigrating to Australia so didn't have to worry about future insurance.
Not sure about tomato soup. But, a couple of years ago my son spilt some luminous green pop on my carpet. I tried a shampooer and all sorts of cleaners, but nothing shifted it. I decided to get a new carpet (Old one had been down 10 years or so). I was telling the lady in the carpet shop about the green pop, and she asked if I was making an insurance claim. It had never crossed my mind, what with the carpet being so old. Anyway, I called the insurance company, they came out and had a look, agreed it was beyond repair and paid for a new one. If you have insurance, that might be your answer!