Those tours are run by Uber Boats/Thames Clippers.
Their normal scheduled river boats run on the same route (and as far east as Barking, Woolwich and Greenwich) until about 9 pm.
In June it'll be light until about 10pm or so anyway, so the last scheduled service would be the one you want at 9.34pm from Woolwich, 9.54pm from Greenwich, terminating at the London Eye at 10.49pm (if joining at North Greenwich, precede the boat trip with the London Cable Car).
There is also a 9.44pm from the Embankment to Putney, which connects with a service from Barking/Woolwich/Greenwich then take the bus #14, 22 or 74 back from Putney to Central London. At any time of year that is an interesting round trip to see London by night.
Sit outside on the aft open deck (it'll be warm enough for that), you'll probably get a better view and experience than on the tour boat which will be using the same type of vessel.