1. Nothing is free. The tax-payer pays.
2. Under the Medicine's Act a provisional approval can only be given on a restricted basis to a limited number of people. Read lawyer Sue Grey's judicial review here.
3. Comirnaty uses new technology, injecting messenger RNA, instructing our cells to produce a spike protein like that found on the surface of Sars-Cov-2. The immune system determines that these proteins are foreign (antigens) and elicits an immune response.
This technology has never been used in humans before.
In the context of the word "effectiveness", it is not known if the vaccine will stop you from catching and passing on the virus (see government advertisement below). The claim is that it will reduce symptoms.
5. There is no "approval". There is only provisional approval.
See 1 and 2 above.