You should be able to get UIM without having comp or collision. AFAIK it's only the liability that it's tied to. Depending on where you live it can be rather expensive, but IMO it's totally worth it. I carry the highest limits of liability on my motorcycles for just that reason. You have to have a motor vehicle and liability insurance on it to get UIM, but you don't have to be operating the motor vehicle to collect on it, at least in Ohio.
But as far as health insurance ... as you've probably already found, you could buy a very nice car every single year for what individual health insurance costs.
Get what you can afford. I'd go for catastrophic coverage that covers a variety of different conditions and treatments, over something with a lower deductible that would probably be useless for a serious illness or injury.
If you're self-employed you might look at a Health Savings Account - the tax savings there are substantial.
Speed comes from what you put behind you. - Judi Ketteler