In answer to your question, Air Taxi work on average pays around £18.00 per hour, not always that many hours though. Expect around 15-20 per week max. Instruction work pays around £10.00 per hour for an FI(R) and £12.00-£15.00 per hour when unrestricted. Some schools also pay a retainer which is normally around £20.00 per day. If you end up luck enough to move onto a Turbo Prop, like me you will probably end up offering your time for free.
If you have the facilities and the capabilities, it is not a bad idea to set up a business to provide income to cover the standard living costs giving you the flexibility to fly whenever work is available. This way has worked well for me.
But then you never know. Go for it, take the chance and you may just walk straight into a job. It does happen.
Good luck.