The Pensions Regulator is responsible for ensuring compliance with the auto-enrolment legislation; where there’s a breach it’ll initially focus on education rather than imposing fines for non-compliance.
If your employer doesn’t meet its duties, The Pensions Regulator will initially just tell them to put things right. Any further failure may lead to the government fining your employer a lot of money. In the event of persistent and deliberate non-compliance, The Pensions Regulator can issue increasing penalty notices of up to £10,000 a day. Ultimately your employer could face criminal prosecution and even imprisonment.