There is a facility called The Armitage Storage which is actually the only one in Central London believe it or not! It is very reasonable and they collect for free within 2 hours of booking online or within a 1 hour time slot. They also offer a redelivery service but you can also access your stuff at anytime, 24/7. Each unit is individually alarmed and climate controlled so perfect for storing wine, art, sports equipment, bikes, furniture etc. Great service, I highly recommend them, its like having an extra room!