The description “lie flat” is normally used to refer to products which are “flat” but nor horizontal to the floor of the aircraft.
The preferred term for seats such as BA’s Club World product is “fully flat”, horizontal to the floor, which avoids confusion.
Club World is not at all claustrophobic, and while stepping over the footrest is a non-issue on a day flight, and easily accomplished by most able bodied people even if the footrest is “down” there are two seats together at the rear bulkhead which have direct aisle access and do not have footrests to negotiate.
If you are less mobile, having two aisle seats can also work well if travelling a deux.
Book before June 4 (sale ends then) and seek out my post on Taste of London or mbna discount codes.