caravan would be good, low (ish) DOC good payload and range, most importantly single pilot IFR. You will find aircrafts fill up very quickly, so you need to be sure of what you are transporting i.e no furkin great boxes etc. Also on a larger scale but relativly cheap is the shorts 360, good for those short night hops.
There are not that many aircraft that are suitable for what you have in mind.
Also to consider, you need a tonne of cash probably £200'000 + to cover all costs and payments for aircraft and at least 3 months trading without earning a bean.
To conclude, its not a smart idea simply because it is financially out of reach for 99% of people. You wont get credit from a bank, and to make matters worse the price of oil is rising which will seriously affect your bottom line.
Don't get desperate because to cannot secure a job it takes time. I am unemployed as well after my airline gave me the dagger.