Just to repeat what everyone else has said, you do NOT want a car for London.

And although you don't need to stay in the city centre, especially if your hotel is very near a station, where you are currently staying is a VERY bad location.

It seems to be in the middle of a business park, a big distance from the nearest train and underground stations.

If you can cancel, I strongly suggest you do so. If you can not cencel and don't want to just book somewhere else anyway, then a car might come in usefull - just to get you to a station! etc.

Book a different hotel in the centre (check with us first if you are unsure about location and price), it will probably be the best use of your money.