I find 'Dextro Energy' glucose the most effective tablet. A mild hypo, one or two tabs fine, a worse one four tabs works. Chew them and let the glucose sit in your mouth for a while before swallowing - it can pass through the mucous membranes into the blood faster than through the stomach (this doesn't work with sucrose as it has to be digested first).
Important to sit down and let them take effect (5-10mins), otherwise it is very easy to keep chomping on them because you still feel bad and dizzy - then the subsequent glucose high can be stratospheric. The dextro energy tabs come in various flavours, I find the Lemon and Tropical the most palatable. Also, if you open a pack but rarely use them be aware that they become very hard and almost impossible to chew when you need them fast!
Lloyds chemists often have them on 'buy two get one free' offer.
Lucozade is very effective but very easy to overdo it unless you measure the volume before drinking.
I also keep a tube or two of GlucoGel in the car and in my bag if hiking - it works VERY fast (again, keep it in the mouth) but is expensive.