If it goes before a magistrates court, he'll still get 6 points on his licence. (It could theoretically be up to 8 points but that would seem to be extremely unlikely in this case). The fine will be between 1.25 times his weekly income and 1.75 times it. Note though that if his weekly income is less than £120, the system will regard his weekly income as actually being £120.
So, if he's (say) only in receipt of JSA (or its Universal Credit equivalent), the fine would be between £150 and £210, which is less than the £300 fixed penalty. He'd still have a £34 surcharge to add onto that though, possibly with costs to pay as well, so he wouldn't necessarily save that much.
However if, say, his income is £500 per week, the fine would be between £625 and £875, plus an additional 10% surcharge and costs.
There's no relevant driving course option available in such circumstances.