If you only have time to see one mid 60s movie built around an English band who aren't The Beatles, please don't let it be Seaside Swingers. Pick Ferry Across The Mersey with Gerry and The Pacemakers or Having A Wild Weekend with Dave Clark Five or even The Ghost Goes Gear with The Spencer Davis Group, but unless you're really want to be bored to tears, don't let it be Seaside Swingers.
The main reason Seaside Swingers is so bad, compared to those other films, is that it isn't built around Freddie and The Dreamers, even though the movie poster would lead you to believe otherwise. Instead, it's light romantic musical comedy, which includes several dance numbers in the style of Oklahoma or Seven Brides For Seven Brothers. Freddie and The Dreamers are only featured in minor roles as goofy cooks. Since Freddie & the Dreamers were a minor British Invasion band, I guess in a way that's appropriate. In Seaside Swingers, they perform one absolutely terrible song and then during a talent show, they sing another song, which is just barely listenable. I still think Freddie & The Dreamers could have carried a move (and certainly a better one than this), IF they had a script written around them.