Oddly, I had the same situation. My second vote was at a primary school across town. I vaguely remembered it but when I got there it was all new houses. Ended up having to collar some random woman to ask "where is the school"Yes but the polling station /school car park gates were still locked at 7.15am.
This nearly threw me. I'm too unfit to clamber over the fence and ramming them with the milk float seemed drastic.
A side gate was open. Crafty beggars.