Idiots guide to grow lights

After much dithering and procrastinating as to whether to invest in a pre made growlight thingy I've bought something.  I looked at building something myself but space, ability and where was a problem.  I looked at a ready made growlight/propagator system the Vitopod but it was £150+, then a Garland Growlight Garden at around £80. For my first year sowing really early and not knowing whether I will do so again I thought to find a less expensive alternative.  So I bought a cheap  LED light cluster that will clip on a desk in the spare room.  Seedlings seem to like it so far, but I'm not expecting too much for £17.

Looking good Jen, I like the background beers

I'm hoping to set mine up at the weekend so will post pictures then.

How long do you intend to leave the lights on for?