County councils have a statutory duty to see that recognised footpaths are kept clear. You may be able to get action from them. Usually, they try to work with landowners. Sometimes they will reimburse local councils for money spent on footpath maintenance.
Another source of help is Community Payback. Sometimes local organisers are keen to find useful work for people undertaking Community Service, although it is important that tools and proper supervision are available.
Scout groups are also sometimes looking for useful experience - again supervision is very important.
As you suggest, these days we have to try any and every source of help!