Update as requested!
I initially spoke to the current supplier of the new property who 'would be very happy to replace both meters at a cost of £50 each'! No way! I then decided to approach the supplier who we were just about to close our account with at the previous property ... I wanted to see if loyalty counted for anything and, lo and behold, it did! They (Atlantic) are going to switch us over to normal credit meters within two weeks of us switching over to them, at no cost to us whatsoever! We're very happy customers indeed :)