Business class 1 car insurance.

Bigphil1474

I've had business class 1 use for the last 30 years working for a local authority using my car to drive from site to site. As above, carrying equipment isn't an issue (but unlikely to be covered if expensive equipment), and carrying colleagues occasionally is okay. Mine is a negligible cost as an add on as far as I know, but I've had it that long so not 100%. My named driver is not covered for business use. 

To be honest, my experience and knowledge of private care companies is that most are cheap skates and exploit their employees massively. I hope yours isn't the same. However, they are talking nonsense saying Class 1 is sufficient for client transportation. You will probably need commercial insurance if carrying clients i.e. even Business Class 3 isn't suitable. Is it an expectation of your job role i.e. in your job description?, or is it basically your employer relying on your good nature to go above and beyond. If the latter, then they are probably breaking employment law.

You should generally be paid an hourly rate (above minimum wage) and motoring costs on top, if you are expected to use your car for work. IME, they probably won't be bothered as they can just get someone else in, pay them crap wages, and exploit them, until they learn what's right and go somewhere else. You tend to be better rewarded financially from working at a checkout in Aldi than working as a care worker in the UK.

You could look at claiming some tax back as you can receive up to 45p per mile (50p with passenger) tax free and if you are getting nothing, then that's tax you can claim back - might need an accountant (?), and you are probably limited to how many years you can claim back. You would also need records of all your journeys.

You should also be paid whilst driving your clients around. Personally, I'd be taking them in a taxi paid for by the client or your employer.

Castle

It's the current tax year and the previous 4 years.
Claim tax relief for your job expenses: Vehicles you use for work - GOV.UK (www.gov.uk)