The offences potentially include insecure load (it shouldn't drop off), unlicensed carraige of waste products (if you don't posses a current Environment Agency Waste Carrier Licence) and fly tipping (if you leave it there), etc. You may also be in breach of your trade use vehicle insurance if carrying waste materials without an EA licence.
Insecure load is possibly a £100 and 3 points if the magistrates are lenient, always assuming it hasn't caused an accident and nobody got injured...
Transporting waste without the appropriate licence can be a fine of up to £5k
Fly tipping is more serious with possibly unlimited fine (used to be £50k), up to 12 months imprisonment, and they can confiscate your vehicle
Of course, in addition if your insurance doesn't permit the carraige of waste or requires you to have an EA licence, but you don't, you could also be looking at driving whilst not in a accordance with your insurance - or basically you're uninsured. Another fine and points.
And that's if your load isn't classed as hazardous or reportable (Japanese knotweed, maybe?)
The one to watch out for, though, is the EA licence - if you get pulled on a VOSA roadside check, that's one they seem keen on. One of the carpet fitters we had on a job three or so years back got caught that way (carrying waste adhesive tubs and carpet offcuts plus other waste). They weighed his van and found he was 200kg over the rated limit for his Astra van, so he got done for that (and had to reduce his load and pay a taxi to remove it and some of his tools for him), then they did him for no waste licence on top. Cost him well over a grand. Plus the taxi fare...
Were I you I'd start packing to leave the country now...
PS This is NOT bull hockey