welcome to GoY
I think you mean weevils, the larvae of the vine weevil are white grubs about 1cm long with a brown head.
there is a provado product that you water into the pots to kill them. alternatively regularly knock plants out and check the roots for grubs. a 1-2cm top layer of grit also discourages the female from laying eggs.

as for cats there are several products on the market. we find throwing wet sponges, supersoaker guns or hose pipes as good an option as any.

a friend who worked for the rspca suggested a kids spud gun as the potato pellet hits but doesn't hurt. unlike any other typr of pellet.

but sadly I don't think anything really works.

Well there is something that works to keep cats out , but its a performance to set up if you want the proper kit, which is connected to a water supply and an electrical supply. A lesser, battery operated version here https://www.amazon.co.uk/PestBye-Battery-Operated-Waterproof-Repellent/dp/B004SGC75S but you'll probably need more than one.

As for weevils, maybe you do mean vine weevil beetles, but there are many more varieties of weevil in the UK, not sure which you mean.

Having your own cat sometimes works. Having a small dog such as a terrier works too. They tend to prefer areas of reasonably well cultivated unplanted ground, so keeping the beds closely planted deters them trying to dig holes.
To keep them off seed beds etc prickly twigs or leaves such as holly or bramble over the area should do the trick. For vine weevils (pesky things) you can't do better than follow Seaburngirl's advice.

As someone who has three cats who roam our garden as well as our neighbours gardens, and someone who has other peoples' cats visiting our garden, I find the best way to send them on their way is throwing a jug of water, even the noise of the water hitting the ground or fence seems to get the message across. I would never throw anything AT a cat, in case I inflict injury, even loud hand clapping can send them on their way. Of course cats will use gardens as toilets, that's just the way they are. Frequent patrolling of our prized flower beds with a trowel and a poo bag ensuring the garden is poo-free is how I deal with it. There must be around 20 cats living nearby and quite a few pop into our garden for a visit - our cats tolerate some better than others.

Can I also add, a spud gun shooting things could inflict injury to eyes and ears, so I would not recommend that method!

that's fine if you have cats and don't mind doing the poop scooping. but I don't have cats or dogs so I don't see why I should poop scoop someone elses pet's mess.

one of my neighbours is quite proud of the fact her cats don't mess in her garden. Charming!

It's said to be only the dominant cat that doesn't bury its faeces. But probably not all cats know this......

In my experience, its tom cats that don't bury their faeces - females always try to, even if they're not always successful. Tom cats often choose long grass, such a delight when you come to cut it...

It's been a while since I have been on, not that I haven't read the blogs and questions, just no comments or blogs. This one struck a chord as we have a (I think feral) cat which visits and I try to chase out, not that I hate cats, we always had cats when I was young - decades ago! The thing is when we moved here the previous owners had cats and the bird population was very minimal - just scores (Literally) of pigeons living in the Leylandii. After a time we gained birds, now we have hundreds, even the sparrows are back and the Thrush. We feed and they have loads of bushes and ivy for nesting - we don't need a cat! I have seen one in the past waiting for the unsuspecting baby Moorhens to bounce down out of the tree they hatched in - only to be eaten by the cat. While in the garden centre waiting, there was chap in front who had some spray in containers which said cat/dog repellant, so I asked if it worked and he said yes! All I need now is to go and look and see what it was!