Hello David.
Having read the thread from a year ago I can see this is a real ambition of yours so I'm going to try to help if I can
It's sounds like you have some help but need a business plan of sorts to get that help, am I correct???
A business plan can be very simple.
Start by getting a hard back type folder and filling it with paper. Every time you have a little idea to do with work write it down, I have severe ADHD and dyslexia and it's the only way I can cope!!!!
You already have a good idea about what it is you want to do so we know where we are going.
List everything you have that you think can make you money directly or indirectly in arb.
For example, if you have a lawn mower, write it down. Strimmers, hand tools etc etc.
From this list work out what services you can offer. So if you have a lawn mower you can instantly start mowing gardens. And like wise hedge trimming if you have trimmer.etc etc.
GET SOME INSURANCE. It's a Google search and one phone call
Once you know what services you know you CAN offer, make it happen. Get onto vista print. Spend £15 on some business cards. Throw them everywhere, shops, bus stops, through doors, pubs everywhere.
Wait for the phone to ring and be smart, charismatic and efficient and your customers will have you back time and time again.
Once you are bringing in some money and you are confident it's working you can start to look at where you WANT to be.
Your best asset at this point is the fact that your mowing customers will know you, like you and put you first on the list for tree work
Invest in yourself, get your tickets, buy a saw. Start by doing bits and pieces and if your good it's a very organic proccess and you'll be working with a saw all day every day.
But don't forget your mowing.
I hope this helps, and doesn't sound patronising:)