If you have more than 2 medium size suitcases and 2 cabin size bags, you will probably struggle to fit them in the boot of a standard minicab as they aren't very big.

If it's just a bit more (for instance 2 large suitcases and 2 cabin size bags), request an estate car, if it's quite a bit more than that (e.g. 3 large suitcases + 2 cabin bags or more), then I'd recommend talking to the minicab firm in detail as you might need a people carrier.

Some minicab companies that serve LGW-LHR route have developed a rather nasty policy of charging £10 or more for extra piece of baggage even if only a standard vehicle is required, so do check carefully in advance with them.