Whilst I admire your enthusiasm, I think you need to learn a few things:

Firstly, the parts that are readily available in England are geared towards Featherweights, for which there a lot of events all over the place. If you are going to build robots for your family to use, and you don't want to do them as small as ants or beetles, then I would highly recommend building a FW rather than a Light or Middleweight. Besides, at least then you can use them at the live events.

I have also noticed that you haven't actually built a robot yourself, so I would highly recommend getting yourself to an event and finding out HOW to build them before you set about building multiple robots.

Also, it's spelt Guiness .