Not really - 3000 people across the entire UK is nowhere near enough (it works out as one tester per 21000 people); even if they all worked 9-5, worked solo, didn’t have lunch, managed to travel between appointments and conducted them all in an hour (and every client was at home when they are meant to be), handed their test kits in during their own time and none went sick you’d only get a maximum of 24000 visits a day.
Realistically managing half that would be really good going, and given the infection rate indicated by this app if this disease comes back properly is going to be in the low hundred thousands of possibles per day it should be clear they should be aiming for ten times that number doing visits (at least).
London itself needs probably around 5000 to 10000 people doing the visits, probably working seven am to eleven pm, seven days a week.