Hi Joe...
If you are on any income related benefit including Pension Credit , ESA (income related ) JSA(income based) or Income Support the you passport to free health care costs (prescriptions , travel to hospital, prescriptions etc).
If you are on contribution based benefits (JSA (first six months are generally contribution based) or any group of ESA (first 365 days of the work related group are cont based , and the Support group is cont based indefinitely if you qualify) then it depends on other income you have , and you will be excluded from getting an exemption from health care costs if you have £16,000 in savings, investments or property (not counting the place where you live). Remember your partner's income is also taken into account.
The rules are different in part if you live in Scotland , Wales or Northern Ireland
Firstly have a look here
Low income scheme to see if you are eligible for the low income scheme, and then telephone the NHS services Authority on that link.
If the £300 is a bill from the Dentist and you qualify for the low income scheme then you
may be able to claim a refund using a form HC5. I would also consider putting in a complaint to your dentist with regard wrong information.
If the £300 is a demand from the NHS Business Services Authority then be aware that there is a £50 surcharge if not settled within time limits and will be pursued through civil recovery.
Another point to note is that if you are in the support group , it could be that you will be eligible for an element of Disability Living Allowance ,motability car, bus pass, help with adaptations to your property from the local authority...etc have a look at
Direct.gov disability pages.Are you aware that you can pay for your medication prescriptions using a pre payment card , which could drastically reduce the cost of prescriptions.
Hope this helps , but may not be the answer you were looking for .
Rich
"The difference between 'involvement' and 'commitment' is like an eggs-and-ham breakfast: the chicken was 'involved' - the pig was 'committed'."