You can spend your Maintenance Loan on anything you want. Nobody monitors what happens to the money once it arrives in your bank account. At that point it's your responsibility to manage it.
For most people it covers the cost of accommodation and leaves a bit over for food etc. Those on the minimum loan will find that it doesn't even cover accommodation - they need to top up with their own savings, help from parents, a student bank account overdraft or by getting a part-time job while they study. The lucky few find that the loan comfortably covers their accommodation and leaves plenty over for other expenses.