To be honest, while taking on a house robot can be a fun thing, concentrate all of your energy and focus on getting a robot built that can beat other featherweights first. The chances are that to do any damage to a house robot on the scale you are thinking of, your robot would have to be built like a brick structurally and that would leave you no weight for a weapon.

The only robot I've seen (through the medium of video) that successfully took on a house robot was Little Flipper lifting up BattleAxe (120kg, not 1000kg+). Now, all the Nipper machines are extremely well built but all Little Flipper could do once it lifted BattleAxe up was, err, put it back down again, because they couldn't drive anywhere with 120kg on top of their robot.

It was a lot easier on Robot Wars to take on the house robots as the size/weight ratio between competitors and house robots wasn't as great as that between feathers and house robots. So focus on getting your robot running and getting enjoyment out of fighting other fw machines first.

(P.S. Major Damage is a sissy )