Hi Kate, I have just moved into a new McCarthy and Stone Flat, and talking to another resident it appears the Meter does stay set to GMT and remains on that during Summer, you have two options as I see it ..
1 Alter your Heating and Water Time Clock when the change occurs back to GMT because this clock adjusts itself for BST, this puts you in Sync with the Meter, or ….
2 Leave the Heating and Water clock time, and set the Water and Heating times to come on 1 hour later in the Summer for each period you have set, unfortunately you lose an hour on each period doing this, so may not be enough for your needs.
I think I will just change the Timer on H/W to GMT next month it may be easier,
Hope this helps Brian