The British Museum does have the facility to accommodate coach parties visiting the collection to park nearby, however, very few of the other attractions can allow coach parking other than by prior arrangement and even then it is strictly reserved for disembarkation for parties who might not have good mobility (for example coach trips for the elderly or disabled groups).
Large coach companies should be aware of feasible setting-down and collection points near to the various destinations, if you are unsure as to the logistics of delivering your party to the door of the theatre, gallery or museum you are visiting, make inquiries with the coach operators before setting off.
For more information, please visit Transport For London (new window) and telephone number is 020 7222 1234.