I am having real problems when shooting in clubs (i.e. very low light) whereby I am getting huge amounts of overexposure on blue and red lights in venues which blow out all the detail in a shot. I assume the solution is to keep the aperture as closed as possible to combat these bright flashes?

Not really, because everything else will go dark then.
Every medium has a certain dynamic range, this is the amount of stops of exposure it can capture between burnt out white and jet black. Typical video cameras tend to have around 10 stops or so.
In practice what this means is that you often have to sacrifice certain parts of a scene which like yours will be well over the range of your camera.
In post production you can select those colours that are burning out and darken them leaving the other areas alone.
Steve

Thanks Steve, will certainly try that. Reds in particular are particularly bad it seems but hopefully will be able to correct this a little

It will help if you flatten your image quite a bit. Go to the Neutral setting and use that. I'd crank down the contrast to the minimum and also take the saturation down more than the setting has as well.