Hi, Bill, if you're working with the Airfix kits, you want a glue for styrene. I recommend using liquid as well as thicker tube glue.
Glue for styrene works by melting the joining surfaces and welding the parts together.
There are many brands available, and they all have their adherents (no pun intended, but I'll take it
) I use Testor's tube glue on my styrene models, and Plastruct's Bondene or Weldene, which are liquid. Testor also makes a liquid glue, and I understand that Tenax works in the same way by melting the material to form its join. I don't know what's available to you in the UK, but look for liquid and for tube.
Each has its use. Tube glue is thicker and sets in a couple of minutes, which gives you time to adjust the pieces if necessary. So, you can apply it to the mating surfaces and then assemble the pieces, for example, putting a drop on a pin that fits into a hole, or putting the glue into the hole and then inserting the locator pin.
Liquid glue is usually applied with a brush, or with a pipette applicator, or even a straight pin, and it is applied to pieces that are held together and it flows into the join by capillary action. For example, I use liquid glue to assemble two halves of an aircraft fuselage, by holding the halves together and flowing glue over the seam, often from inside the model, with a brush.
I think you'll find that you'll have use for both kinds, as you proceed.
I do not recommend using cyano-acrylate glue, also known as CA glue or Krazy Glue (one of the brands sold for household use), or 2-part epoxies, for this application. They may form strong bonds, but they do not weld the styrene as styrene glue does, and such bonds are more liable to break under shear forces (if the figure should get knocked over, for example), than the styrene weld is. CA and epoxies are better for resin or metal, or for bonding unlike materials (like photo-etched brass to a styrene figure).
Hope that helps, prosit!
Brad