Erm, why should low earnings be a barrier to entering into VCTs?
A £25k investment eats up your entire 20% tax liability. That puts you in a position to pay the entire 40% component into pension and charitable contributions, and give HMRC the finger!
The only thing that'll stop me doing that is if I take advantage of the stamp duty holiday to buy a house (so my funds get diverted). That becomes a real possibility if the new government stops pouring taxpayers money into propping up the house price bubble.