Take an electric train from Baltijsky Vokzal to Lebjazee station. It is seems the frontier-guard zone not valid now though warning inscriptions are present everywhere. But nobody shoots and does not fine on 5 MROT (minimal wages in Russia Federation).
PS 2004: Alas, according to the last info there is frontier-guard zone really and cordon on the road near to Lebjajee, so you will need an official permission to enter.
If you get to Lebjazee, you should go on the crossing road with railroad, cross it, make a right turn and go to highway Krasnoflotsk. Then go down on the highway to Krasnoflotsk direction near to 4 kms. There will be rather low brick wall with russian inscription - "Fort Krasnaja Gorka" and way to the right. There is near to 1 km to the WWII memorial and the Fort.
Seraja Loshad battery. You need a car. After Lebjazee you can choose the road to Sosnovy Bor and get to Pulkovo village right turn. Than drive down to Finnish Gulf shore and further by the road down of Grafskaja Lahta Bay till the gates of recreation camp. Than by foot near to 500 meters. Gora-Valdai battery is located on the south shore of the bay 1.5-2 km to the West from Seraja Loshad battery.
PS: Photos of Gora-Valdai turret battery were placed in "Krasnaja Gorka" section by author's will because there were not another proper place for it on my site.