So then I may have some work next week going to central London for Laundry but where do I stop for my rest break with usual parking/no stopping issues ■■?
I always liked having me sarnies on Downing Street, or in front of Buck Palace.
Stopping on the premise of one of the locations you are collecting from would be the easy answer - if that is an option?
Hopefully will be able to hang around one of the deliverys otherwise I will try outside queenies there is plenty of open areas there
At your drop points. As soon as you are done doing the work bang it on break. I do London quite a lot, using customers yard/premises is a must.
Take a 45 minutes break before entering London, never assume there is enough driving time to the first drop.
What with congestion or road works, and accidents to delay the trip .
In the suburbs after my last drop, I may pull in to a loading bay for a coffee stop ,as long as its quiet .
Central London is no stopping area anywhere with double red lines designed for traffic flow .
Yellow box junctions are monitored by somebody watching on Cctv .
Check out the posh top totty, give them a toot and wave, they love the attention .
Don’t go to the Grange Tower Bridge hotel on Prescott St.
Just spent four nights there with the missus, and what a waste of time it was. The language barrier between us and the staff was terrible, phoning the concierge asking for more toilet roll, and they reply “you want more bath robes!” NOOOO 
If you drive past it on your travels, then just keep going!!
Cheers 
Last time I found that I needed a 45 break there I asked a parking warden who directed me to a double yellow lined side street with instructions to put a note on my windscreen along with their warden number
10 out of ten to that warden then!