I have a Raynox DCR-250 and a 150 for when not such strong magnification is needed (ie, the whole of a butterfly as opposed to just the pattern on a wing).
I adore these two lenses.... they are spring loaded clips and just clip onto the front of the 50mm lens....or any other up to 62mm I think.
As with any macro I think, you have to focus as close as you can then move the camera forward and back to get it perfect....a tripod is the order of the day.
All I can say is that I recommend them..... I'll leave it up to you to decide...you can get them from Jessops I think.
PS. Is it supposed to read "somerserset" in your location?