I’ve heard that the Airfix Vulcan is a bit of a filler queen…
Re masking – isn’t it an all over green & grey camouflage scheme? Mask the glazing with Tamiya masking tape, cut to shape in situ, and paint the undercarriage wells with Humbrol Maskol
If you don’t have an airbrush, Tamiya and Humbrol do rattle cans which would be fine for a model as big as the Vulcan – try http://www.modelhobbies.co.uk or your local Hobbycraft store
I use a cotton bud for the Maskol as it eats brushes.
Do not fit the wheels at this point; fit the undercarriage doors in “in flight” mode using more maskol as a temporary glue.
Spray the whole thing with the grey first, then the green. I would do the green freehand but you could use maskol to cover up the bits you want to keep grey and then spray the whole thing green
When the green has dried, peel off the maskol and tidy up the flaked off bits of green, then give the whole thing a coat of clear gloss varnish – I find it helps the decals settle. When all decals are done, go over them with more clear gloss.
When that has dried, a coat of clear Matt varnish helps it all settle down. Remove the undercarriages doors and all remaining Maskol, then fit the undercarriage. Et voila
Scale Aviation Modeller International is a useful magazine for more tips as well as kit reviews. Bigger Tesco stores should carry it