You can reach Gatchina (Krasnogvardeisk) by the electric trains from Baltiskij railway station in St.petersburg or by the buses from Avtovo metro station. It is not a problem. Villages Pudost and Mozino could be reached by the electric trains too. Krasnoselskij sector: you need to get to Krasnoe Selo town by electric train or bus and then take a bus to Russko-Vysotzskoe village. Slutzko-Kolpinsky sector: you must get the buses from Kupchino metro station to Jam-Izhora and Kolpino.