I did a design degree over 20 years ago (not graphic design) but life pulled me in another direction. It's been fulfilling and I plan to continue (part-time) in the field I've found myself in.
But helpfully, at a time I need to earn more money and am keen to flex my creative muscles again, I've fallen into being in demand for my design skills, laying out visually appealing publications for my employer.
This has happened before in previous jobs - they like the way I make my work look, so ask me to do a bit of this and that. But with my current employer, after them having paid me additional hours on payroll to design a 28-page guide, they now want me to design a suite of further publications, but for me to invoice them as a freelancer.
I want to do this work. I need the money and I'm loving being creative again. I just hadn't planned to plug this gap until my youngest starts school in September - so until then, time is tight to do the work, to develop myself, and to wrap my head around getting myself set up.
I have a few questions which I'd really appreciate help with from those in the know:
(1) What do I charge my employer (small national non-profit) as a freelancer? I'm not a complete novice – I've been 'dabbling' in this for years. I have a good eye for layout. But I'm not formally trained and I don't have InDesign or know how to use it (yet – that's on the autumn to do list). I use Publisher and push it to its (frustrating) limit. I'm going to have a new HMRC admin burden initially from freelancing, plus further costs in time (software, hardware, etc.), which I'll need to factor in. Because I have annual leave and sick pay through my employed work already, I'm wondering if it would be disingenuous to factor this in too?
(2) Do I need to set up insurance (or anything else) if I'm going the self-employed route?
(3) Do I just need InDesign, or shall I pay for the whole Creative Cloud suite so I have Photoshop and Illustrator too?
(4) There are no graphic design courses available locally and I'm tight on time for self-development. How can I efficiently add to my knowledge and skills - for example about colour, setting up optimally for print, typography, design/layout theory and more? Any good books, blogs or tutorials anyone would recommend? Anyone want to mentor me?! 
Thanks so much for any advice. I need to go back next week with a fee …