Одна фраза и четыре очень полезных слова.

If Britain wants to benefit from the single market, which eliminates (to get rid of) all tariff and most non-tariff barriers as well as customs control, it will have to abide by (to accept or obey an agreement, decision or rule) most European laws, including the free movement of people from other EU countries and huge clutch (the complete set) of single-market regulations that are ultimately (in the end, finally, after a series of things have happened) enforced by European Court.