How about starting up a lawn mowing service come gardening round? I know you'll only have a few months now but someones trees need pruning every 3 years where as a lawn needs cutting every week.
All you need is a lawn mower and strimmer and no big waste to take away. You won't have to travel and if you can sign on your truck/van you are also a qualified tree surgeon you'll pick up treework on your rounds.
This is where I started from and built up. Put local ads in papers and do some cheap flyers to the tune 'Regular lawn mowing and garden maintenance, local person, honest, hard working and utterly reliable. No job to small. Good rates and friendly service is our trademark.' Or some such. You shoud be able to charge £12 to £15 an hour. As more work comes in increase your rates and charge for waste removal of grass cuttings etc. Mention the tree work later when you've got to know your customers and they'll spread the word for you.
You can save for a chipper and then when you start to let your gardening folk down as the treework comes in you can start giving it up (awkward and late paying customers first).
The less work you have = less people see you working = less work generated and it's a bit of a downward spiral so first off you need to get back out there where people can see you working. I pick up 30% to 40% off my work from people seeing me out and about.
Don't listen or take to heart what one company has said to you... there's plenty t**sers out there knocking you down just don't let 'em!
Treework has suddenly become a much more competitive business in many ways i.e. larger firms laying off and so loads more smaller ones have popped up. I've been going 7 years and can honestly say that there is no way I could start a dedicated arb business now and survive purely on that... there are just too many people working in this area.
Good luck with how it goes but don't feel if you're cutting lawns and pulling weeds you're not a proper arborist - you have to do what you can to get by. You sound quite young so you'll have plenty of time in the future to climb about in trees!