Scottish Power, don't get caught out !!

SwanJon

British Gas checked/adjusted plans every three months a while ago (when there had been a few pprice changes in 18 months) to try to make sure no one ended up with a sudden increase. They've since gone back to 6 monthly.
It could be SP are doing this with new accounts until they have a years consumption history?

Pro bono
Electricty readings are in kWh so they're easy.
Gas depends on your meter
Older imperial meters measure in ft cubed, generally have 4 numbers and are bluey-grey. The calculation is involved, but roughly 30 kWh to 1 unit. This depends on the quality of the gas - in some areas it may be as low as 15, but there's only about 700 houses that have that high quality gas.
Newer meteric meters measure in meters cubed, generally have 5 numbers and are white. It takes 2.83 m3 to make 1 imperial unit, so each one is about 11 KWh.

MarkyMarkD

If you look at your gas bill, you can work out the conversion factors from units to kWh. Then you can put them into the comparison engines. You need your bills a year apart to be able to accurately see your consumption and both readings in the calculation need to be actual, not estimates.