Welcome to the forums! What car are you currently thinking of getting from them?
Check out Insurance4CarHire’s excess policy. You would still have to pay the amount that ONTO Invoice you for damage or insurance claims, but you should then be able to claim it back.
That’s what many of us here have went for. Alternatively ONTO Themselves are apparently working on bringing back their own excess reduction scheme in future, but this will likely be a fair bit more expensive than the I4CH Policy.
Obviously you should check the terms carefully to make sure that it is suitable for your needs, but I personally have this policy and no complaints to speak of from my end.
PS. It’s worth noting that the £1000 is the MAXIMUM Excess, should it go via insurance. Your maximum liability (should you otherwise be eligible to claim on the insurance policy) would be that amount. Of course if it’s just a small scratch to your alloy wheel then you would only be charged the much smaller cost involved to correct this, rather than an insurance claim going in. They also have a fair wear and tear policy, so smaller everyday marks may not even be chargeable at all.