Worth mentioning that a modern apprenticeship (to level 3) takes 3 years and that you'd need to be at least level 2 to get any sort of wage. As to interior fit, especially on old/listed buildings, I've found that sort of work requires a bit more experience than the average level 2 or level 3 improver has unless they were apprenticed in that area and have knowledge/experience of some of the older techniques. In this part of the world a site joiner (carpenter) is expected to be able to do a full build, from hoardings to roofing (admittedly truss), windows doors, interior fit (skirts archis, etc), kitchens, fitted bedrooms etc. A lot of agency guys I've worked with can't so they get bumped off pretty quickly. The more you can do, efficiently, the longer they'll keep you, although your first few years are likely to be pretty tough I'd say