Sorry, I wasn't clear in my post. To set up an organisation that can apply for grants the majority of the 'officers' or organisers or management board should be people who are unpaid. To establish a charity you usually need 3 unpaid officials - including a chair and a treasurer. If you wanted to be paid you would have to be 'employed' or commissioned by the board to undertake the work that they (as Trustees) deemed necessary. You could not be part of that decision. You cannot be the sole organiser, and be paid for your efforts. If you were doing that you would effectively be a self employed business (albeit with a beneficial social aim). And as a business you would not be eligible for most grants.
A charity or CIO needs a strong and clear governing document setting out the demonstrated need for your services / product (real hard evidence, much more than 'other likeminded people who thinkg there is a need'), and clarity about how you meet that public need, in a way that is not met by other organisations. You need clear systems of governance - how decisions are made, who is accountable. You need an annual report and accounts. You need to set up banking arrangements. Please do not underestimate how much work this all takes - none of which you can be paid for.
By 'challenging' I mean for example that there are many, many more organisations seeking funds than there are bodies who offer grants, it is the most competative time I've ever known, and you will be up against professionals who have years of experience and make grant applications as part of their career. Most grant giving bodies have quite narrow specifications e.g. people living in a specific area, or of a certain age, or within a specific index of deprivation. Researching grant opportunities and gathering the required information is a vast job in itself (unpaid). There may be stringent requirements around your (agreed and published) policies on diversity and inclusion. You will have to know how you will monitor and measure the impact of your work - how many people benefit, what change you are expecting, how you will know it has happend. This is more about outcomes than outputs. Four thousand people receiving a book or other information means nothing if there is no subsequent and measurable impact or change.
There are often quite long times lags - deadlines for the grant giving commitees to meet etc.
If you don't personally know anyone else who supports your aim then I honestly can't see how you can get this idea off the ground. Do you have strong connections with the 'community of need'?
In your opening post you say "a charity with trustees might be inflexible and the admin element might become very time consuming". The requirement around these (which is not so different from a CIO) is not intended to result in inflexibility, rather the rules and sstructures are there to protect everyone who makes a charitable donationor bequeaths money to a trust, and to ensure that money is being spent wisely, appropriately, and that there is accountability.
Having been on all sides of the equation - an employee of a national charity, a Trustee, a business owner, someone who established a CIO, on the committee of a major grant giving organisation - I agree with @OchreSwan and strongly advise you against trying to do this at the moment.
To be more positive, perhaps start by developing strong links with the people who might benefit from your initiative. Find ways of getting in touch with others who share your views on the need for this, and find out how your values align. You cannot do this on your own.
I'd suggest you also look at the charity commision website and this https://www.gov.uk/setting-up-charity If you, and others, are going to go down this route, you really need to understand what you are getting yourself into, how much (unpaid) time it will take, and how difficulty it might be to get funding.
Then (as a group) you need to spend time researching the possible funding opportunities specific to your defined aims.