M&S get lots of recommendations on here. I'm with petplan which I'm happy with, although they're not the cheapest and their excess for older cats is rather high (M&S offer a no excess option). Make sure you examine the small print in detail as policies aren't identical so you can't just go by the premium paid - sometimes what looks like a good deal isn't because a lot is excluded or the amount of cover is low. Also, it's best to go for a policy that has a max payout per year rather than per condition - that way they will pay out year after year for a chronic condition and not stop paying out when you reach the max amount.
Bear in mind that any pre-existing conditions will be excluded. If the vet confirms that Bobby does have a UTI then that may affect any future claims for similar. I'm not sure if it would but it might so it would be something worth checking out just so that you know.
Hope he's ok, bless him. Best get him to the vets fairly quickly in case he's blocked as that can be very serious.