It is quite legal to arrange for the body to be delivered direct to the back door of the crematorium for disposal with out any ceremony at all. No coffin is needed either, a body bag is perfectly acceptable .
Any type of vehicle can be used to transport the body an estate car or van for example. In this case the only fee payable is the actual cremation charge , around £300 , you can get body bags for £11 each . So a totally legal disposal of a body can be arranged for £311 plus the cost of transport . No undertakers need be involved , anyone can collect the body from the mortuary once the death certificate and the permission for cremation has been obtained. I have found a site on ebay that sells body bags for £5 each if you buy in bulk, I am intending buying enough to sell the surplus ones to pay the cost of disposal for my remains, I could even be in profit.
If the person who organizes my 'funeral' is on benefits they can claim £1200 funeral grant , after paying for the cremation, body bag and a van there will be £900 for a good p*ss up in my local as a 'wake' .
This is all if my first plan does not work, which is to leave my body to be used for medical students to practice on or for research, if they accept my body there is no cost at all and any bits they don't want are disposed of free as clinical waste.