Thanks for the advice, I actually bought some bloodworms today from pets at home. I don't like them as a company but it was next door to argos where i bought the sand so i popped in. To be fair to them, i overheard the guy talking someone out of buying a tiny goldfish bowl and insisting that he wasn't going to sell him fish for it today either so fair play to them for that. I've actually just gave them bloodworms, although I don't normally the feed the evening after a water change but i couldn't resist and they seem to love them.
Now as for me and my LFS's. I'm gonna tell quite a long story so by all means get bored and give up reading!!
I got my tank, a tropiquarium55 about 6 years ago as a present. I used Polhill as my LFS as that was where the tank was from and in hindsight, they were useless. They told me very little about cycling and didn't advise me to or offer to test my water before adding a second lot of fish. In fact I think they let me do it two weeks after the first lot. Needless to say I started to lose fish. They then sold me a load of different home testing kits, again without actually educating me about the nitrogen cycle or anything and needless to say I lost all of my fish. On that I gave up, re-boxed all of my tank and gave up.
Then last summer i got inspired by a trip to seaworld in San Diego. So I came home and this time went and spoke to a different LFS, Aquazoo in Croydon where I work. They were absolutely brilliant and he talked me through what probably went wrong last time and how to avoid it this time. They also test your water there for £3 a go. A little expensive but they track all of your results and give detailed advice on what products to use for your specific tank. Three pages of computer print out certainly make for some reading on the train home. As I said I can't fault Aquazoo at all really, they are always friendly and I think its the only LFS I've ever been to where I've felt comfortable asking absolutely anything without feeling stupid. They always seem to be honest and although they are a little expensive on things, I trust them and that counts for a lot.
The problem now is that I've changed jobs for a little while and am no longer near Croydon so after scoring a 98% water test in Aquazoo last week, I decided to try a new LFS for my next stock of fish. I'm sorry but I don't remember the name of the shop but its just off of the A2 near Danson Park at Penhill. With them, I have been generally okay with what they told me but I was annoyed that nothing was mentioned about whether I had sand or gravel when I bought my cory's. I had gone in and told him my situation and asked for advice but he said have a look at what you like and I'll tell you whether they're suitable. Fair enough, but when I asked about Cory's he just said that it was good to have working fish in the tank. So as for what I've done now with the sand, I've pretty much got it form you, this website and common sense. All seems okay so far but the water is a little cloudy. I washed the sand loads and loads but I guess it will still take a while to settle down so I'm not too worried about that for now.
Thanks for your help!!