To emphasise the advice in this thread, and add:
- be very very very wary of actor training schools which charge private -school type fees. The acting school mentioned above (evening at Kings Cross - was it The Poor School?) is an exception - if it's the place I think it is, it was run by highly-experienced people in the industry.
- be very very wary of the "must have a headshot" - there is a current dispute over Spotlight, the industry bible fgor casting. That's where a headshot is needed, but, as far as I can recall from students of mine, you need an agent first
- be very very wary of agents who promise the world
What comes through your posts is that you don't know much about the industry, nor does your DC.
What performing do they do outside of school? Are they in the National Theatre for Young People, for example?
The point about drama school (conservatoires in the official language) is that you get proper training, and you get seen by reputable agents.
The even more important point is that to get in to the most influential & competitive conservatoires, you have to audition against 1,000s of others. You soon see where your talent level is.
The most reputable conservatoires now run degree level programmes, so student tuition & maintenance loans are available. So A levels are a must. Competition for places is very fierce. But start with looking at
RADA
LAMDA
CSSD
East 15
Guildhall
LIPA (great for musical theatre)
Royal Welsh
Royal Scottish Conservatoire
There are post-92 universities which try to run conservatoire style Theatre degrees, but they're much more patchy: Chichester Musical Theatre can be OK, for example, but I wouldn't pay the money ti go to Falmouth.
A young boy will have an initial advantage; there are many thousands of pretty, moderately talented young women; not so many young men, but enough that it's still competitive.
In some conservatoires, it'll help if you can move or even dance, and hold a tune. In a career, these things also help!
So some dance classes, and some singling lessons are good things to throw in the mix.