How much money will each of the projects cost keejaay? 12 plots is a very small site - you have a lot of fence relative to the number of tenants - but how about planting a hedge yourselves? If you were really keen you could even grow the hedging stock yourselves from seed, it would take several years to form an effective barrier, but it would cost very little. Likewise with rubbish, it's a lot of work, but is it possible to clear the site yourselves by hand? Disposing of the rubbish can be expensive, but if you sort it it is cheaper - metal you can sell, sorted hardcore is relatively cheap to dispose of because the carrier can re-use it. You could potentially stick it in a great big pile in one place on the site then at least it wouldn't be in anyone's way. Plastic waste could possibly be bagged up and taken away in cars a bit at a time. Wood waste can be burnt. Glass waste is a real nuisance (and I've had loads of buried glass in all four of the plots I've had - why do people do that?), but if you can collect it up and put in it crates and boxes it can be taken away in the boot of a car a bit at a time.
I agree that £50 from the council was derisory, but I think your job as site secretary is to rally your troops and organise them to help themselves.