get some good topsoil deliverd and perhaps some dry chicken manure and dig it in and level it .

I wouldn't recommend chicken manure, too high in nitrogen. You need lots of compost or well rotted horse manure it the soil really is as light and sandy as you describe it will take a while to bring it into good fettle.

I would suggest that if the garden really was a jungle then the soil is fine - things have been growing well with no interference.
People up and down the country who garden in clay will be wondering what you're mithering about.

Clay? Why if the earth were made of gold I know a lot of gardeners that would be fighting over a spoonful of that kind of dirt.

The solution is the same as for heavy, clay soil - humus rich material, as Moongrower says, constantly added, or at least as frequently as humanly possible - that means soil conditioning compost from the garden centre (not potting compost) composted animal manures, leaf mould, spent mushroom compost, anything like that you can get hold of. Using fine chipped bark mulch after planting will help too - it'll break down and add to the humus content.

Buying stuff can work out expensive if you have a big area to treat. You haven't put where you live Alan, but if you have access to any riding stables they often give rotted manure away, or let you have it for a small charge. Wise to check if the hay they have been fed was treated with anything as it grew though. You may have to get it yourself, but well rotted it is excellent as a soil conditioner. Cow manure will do the same job but horse is better.
If you live where there are trees collect as many fallen ones as you can in the autumn, chop them if possible - easily done by running the mower over them, and either heap them up or if you have any bare soil spread them over it over the winter and dig in what remains of the mulch in the spring. Get composting, don't waste the jungle plants you are going to remove. (Take off the seed heads first if you can)
You can often get spent mushroom compost - cheaper than in the shops if you have a mushroom farm in the area.

I purchased a leaf vacuum / mulcher last year and it does a wonderfull job in making leaf mulch. This year I will be mulching my own leaf fall and my neighbors too rather than having them throw out their leaves for collection. I have a horse riding academy near my home and they offer horse manure for free but it is very fresh. I let that age well before I add it to the mix.

We bought a vacuum/mulcher too but it was designed for taller people than me and the bag trailed on the ground and came unhooked, so I had to get non gardening OH to do it...but it broke down anyway. The blower's good for clearing paths but we find mowing the leaves on the lawn just as effective and quick for chopping them up.

Thanks to everyone who took time to respond to my question. I have an allotment near by so I can get some horse manure and will also dig in com post, thanks again.

Alan

Welcome to GoY Alan. It's already been said, well rotted horse manure and well rotted leaf mould dug in. If you have plenty of trees, depending on the type and if you have storage space, you can make your own leaf mould in 12 -18 months ... Saves you a lot of money.