I basically set up the tank in a bucket with the filter running and heater on, then removed and cleaned the algea off each item one by one, putting it back in the tank/bucket after.
I left about an inch of water and the gravel in the old tank, used this to clean the gravel and rocks.
I then moved the gravel across to the new tank. I then half filled the new tank with the old water and transfered the rocks and plants back, then the filter and heater (submersed but off.)
Then tranferred Midge into the half full tank, topped it up with the rest of the old water (seived through a fine net to avoid dirty bits going in.) Added a little water as if doing a water change (dechlor and temp matching)
Turned everything back on!
The tank is looking very nice, very clean water and no more algae (and i've installed a timer to the light to ensure that none builds up again!)
Midge is happy(ish, he's hiding a bit cos he's a little scared i think)
So i'm pretty chuffed, thanks for your inputs all, i'll let you know in a few days if there's been a cycle or not!