No.
It's a really dumb idea. I'm not going to go on and on, but if you value your self-respect, sanity, mental welfare and bank balance leave it be.
If you are remotely serious then I suggest you come out on an FNRttC.
Oh - extensions are the worst of all possible worlds. Crap fees, inexpert clients, loads of competition from builders, conservatory makers and surveyors, horrible legislation. Donkeys could do the work, but it's beneath their dignity. I've only done extensions for free for friends, and that's because it is seriously not worth doing a good job for the money that you're going to get. If you want to do architecture and eat then do transport infrastructure design, and emigrate to Australia. Otherwise ingratiate yourself with a contractor and move in to contracts management - low quality work, zero self-respect, very good pay.
Structural engineering is having a hard time, but it'll turn good one of these days. In, out, and if it doesn't fall down, where's the problem?