It is mostly up to the supplier. Generally if you have a good payment record for 12+ months at one property, you wont be asked for a deposit at another property. The cost for the meter, however, will probably be charged by your supplier whoever's name the account is in. You should certainly ask around other suppliers to see what they would do as one option is to switch supplier before switching meters.
Some suppliers do take advantage of customers with prepayment meters. I saw a letter to a new customer recently that went something like "you are £1.85 in arrears and you have agreed to repay this at £6 per week. Your account has been adjusted".