I am very fortunate to live in a city where 99% of taxis are black cabs.  The most accessible models are TX2s, so be sure to ask that one of these when booking (or at least mention when booking that you are a wheelchair user).  TX2s have ramps which pull up from the floor of the cab (very similar to those used in buses -- described in the buses section) and have plenty of grab rails inside its sleep to hold on to. In my experience drivers have always been very helpful.

Unfortunately there is no discount available to disabled taxi passengers.  That is unless you live in London where disabled residents are entitled to a Taxi Card with which you can travel up to any distance with in London for a flat rate of £1.50.  However when I used to work, Access to Work used to contribute 90% of the cost of a taxi to and from work.  Now I am at college, my college covers the entire fare of a cab there and back.

Even so, apart from my weekly venture to college, I avoid using cabs and opt for using other types of public transport instead because of the spiraling cost of fares.