I'll do it for no salary
First off build some proper prisons on the uninhabited islands off the north of the UK. All in concrete USA stye 1 per cell, no TV, no mobile phones, no gymnasiums, no swimming pools, a budget of £2.50 per day per person for food. Bring back Hanging for murder if the evidence is beyond doubt, these days with DNA there is much less likelyhood of mistakes. Castration for second rape offences.
Any non British passport holder convicted of any offence deported to country of origin without appeal. Only English language in schools and on official documents. If you want live in my country learn the language or **** off. Just for starters