My new place had one of those meters when I went to look round, the leccy provider will change it over if you ask nicely. Helps if you're a previous customer who always paid bills on time, otherwise they might ask for a deposit. If they do then ask them if they are legally entitled to demand a deposit. Then say you'll take legal advice and get back to them. BT used to pull that trick with new phone lines, £150 deposit or no phone. Oftel told them to stop doing it, they kept doing it. Electricity companies are catching onto the same dubious business practices.
I wouldn't be so sure - I work in the energy industry and all the suppliers I've spoken to observe the '12 month' rule on changing pre-pay meters to credit meters. Additionally, there is also a charge to have the meter exchanged in this scenario, my employers charge £60.00 which is in line with what other suppliers seem to charge too.
You will likely get the meter exchanged if you've been with your current supplier at previous addresses and have a good payment history, but you would still incur the £60.00 fee.
With rented accomodation, the landlords often don't like you doing this either as they're left with tenants who move out and leave the final bill unpaid - more of a headache for them. From a landlord POV, pre-pay is less hassle.
As for your landlord having not registered your deposit with a scheme, this is not mandatory - 'good' landlords will voluntarily be active with such a scheme. Hindsight is great aint it.
I wouldn't view a pre-pay meter as a 'bad' thing, the whole industry was brought into line with credit meter tariffs a couple of years back with some people paying less with pre-pay meters than they would if they switched to a credit meter.
