i am hoping to get a new tank and move all of my tanks downstairs into a laundry room but in the winter it get very cold will heaters be able to cope with this
Your power bill may not though!!!
What I would suggest to help you with you power bill is to invest in a heater for the laundry room, either via a radiator or gas, not parrifin or oil, it'll give off a lot of water and possibly fumes. Purchase heaters for your tanks larger wattage than is required and so you can have then turned down. This way it saves the heater being on constantly just to keep the temp steady. The more powerful wattage will draw the power initially, but then it will economise as it only needs to switch on and off intermittently.
Depends on how many heaters you intend to use, make sure your circuit in the house can take the added power. You will need at least a 16amp power breaker and if you have a washing machine and a tumble dryer all using the same circuit you will need a 32amp breaker.