Your dealing with danger here.
Not only your safety, but your insurence policy.
If your house burns down, and it is found to be shoddy wiring by an unqualified/unregistered electrician/handy man, that started the fire, you will get absolutely nothing back from the insurence company.
So make sure you know what your doing..
And just a few pointers...
DO NOT SWITCH THE NEUTRAL.
(sorry for caps, but you need to understand. This is your life we are talking about)
Here in austalia it is illegal and I only guessing here, but i would say it is the same case in other counties.
A bit of background:
In australia the neutral is MEN'd (joined) to the Earthing system in the switchboard before the RCD. This keeps is at earth potential (which is nearly always 0volts).
If you switch the neutral, yes you will break the circuit, but you still have an active that is alive and kicking and the appliance end of the circuit even though your switch is off.
There is an exception with caravans, both conductors are switched, but like you said;
is it sufficient to just disconnect the live wire to break the circuit
yes, only switch active conductors for your situation.
Another pointer..
It is also illegal to use semiconductors and the only form of isolation.
The reason is this.
If a semiconductor fails, It fails in the closed postion, leaving the circuit on.
Which is not good.
Make sure you have a form of machanical isolation (a switch) before the semiconductor.
Im not trying to sway you away from doing this, just make sure everything is safe and legal.
If you feel confident, and get people to check your final approach to the situation, go for it.