Yes, you've got it right A 1956 Popular with a made in June 1956 frame number and with the appropriate engine number prefix, 030B identifuing a 150cc 30C Villiers engine supplied to Ambassador in 1956. About the only mystery I can see is the singlle saddle as the 56 Popular left the factory with a dual seat but often that is a discreet way of stopping people trying to cadge a lift.
Anyway, what do you intend doing with it? With the price of fuel, insurance and so on thundering upwars a small economy runabout starts to look more attractive doesn't it.Easier to get past household management as well.
Tell us more.
Cheers,