Bypassing an electricity meter is simplicity itself. You simply remove the "Company" fuse (which is on the "street" side of your meter) to isolate your supply. You then re-terminate the red and black cables that run from the Company fuse to your meter directly on to your consumer board instead of via the meter. Replace the Company fuse and you're away. You can do this with both Smart and "dumb" meters (though, since the supplier can monitor your usage remotely with a Smart meter, suspicion may be aroused more quickly). Your ruse is bound to be noted if a meter reader looks at your supply as it involves breaking the seals on both the meter and the Company fuse.
The "Don't Pay UK" scheme is not a good idea. Companies can and will enforce payment through the courts and if they fail they will install a pre-payment meter. This will be set to charge at a higher basic rate and will also be adjusted to recover arrears. No, they cannot do this to the entire population, but they can do it to enough to make it a very risky strategy.