1st time hydro

after various soil grows, I have decided to give hydro a go. I have read quite a bit about it and have a rough idea of how to get started, I'm gunna do more in depth reading before I start just to make it right. I was just looking for a few tips, firstly, I'm using a 400 watt light in a grow tent. I am planning to use two 'GT 205i' gro tank NFT systems, you'll find it on this page.

http://www.3countieshydroponics.co.uk/system/index.htm

I was wondering if that would be a good size, I measured them up and next to each other and they would cover 68.75 cm x 76.5 cm. would that be okay for a 1m2 grow tent or should I look for something else.
Also, if I were to go away for a week, what would be the minimum amount of maintenance needed for someone to take care of my plants?
If anyone could answer these questions that'd be great. I only want to grow hydro if I'm gunna do it properly.

anyone?