Hussar 54
Vehicle Type Approval (VTA) might be a little off topic. However, I would think that UK using the issue as a retaliatory tool against the EU, post brexit, might be a little ill advised. Proceed with caution might be a better maxim, especially as VTA is actually a matter set above EU level by UNECE (United Nations Economic Commission Europe) and its WP.29 (Working Party .29) group. The link you provide seems to be slightly misleading in that it gives the impression that the EU sets VTA standards. This is not the case; the EU accepts the UNECE/WP.29 rules handed down (rule taking, as our politicians quaintly term it) and then issues its own Directives for the EU28 nations to implement.
Dr Richard North, yet again, provides interested parties with immaculately researched and reasoned pieces on his blog
here and
here. Well worth a concentrated read if you wish to attain knowledge greater than the sum total of our "government".