If there is no deal and the UK takes no action to introduce its own state aid law, there would be no domestic state aid regime to replace the EU state aid rules. Accordingly, there would be no requirement for the Government to submit proposals for such aid to any independent body, nor would there be any ability for businesses which felt that they had been harmed by such aid to bring actions before the UK courts.
In granting aid, the UK would have to take account of WTO rules and might decide not to proceed with certain subsidies for fear of prompting complaints from other WTO members or unilateral action by those states under the WTO regimes relating to anti-dumping or subsidies and countervailing measures. However, as noted in section 5 above, the WTO rules only apply to goods, not services, and the remedies are relatively weak.
Despite suggesting during the election campaign that "immediate action" would be taken to set up a domestic state aid regime, the UK Government has not (publicly at least) taken any such steps. It is possible that the Government has simply been too distracted by COVID-19 to focus on state aid, but equally, the lack of concrete steps to develop a domestic state aid regime may be a negotiating tactic designed to encourage the EU to reach a trade deal with the UK.
Whether this is a credible threat remains to be seen; a number of commentators have pointed out that the UK is likely to want to have a domestic state aid regime in order to prevent "subsidy races" within the UK itself. For example, without such a regime, a devolved government in Scotland could offer subsidies to businesses within its territory, to the detriment of businesses in England (which would potentially be left without recourse).
Whatever the explanation for the lack of action, there is now very little time left to conduct a meaningful consultation on the UK's future state aid regime if it is to be in place by the end of the transition period. As we have seen with some of the COVID-19 legislation, lack of scrutiny often leads to drafting deficiencies.