Invalid client version

I've looked through previous threads with the same error (Your client is invalid version. Re-install the latest version game client.") but no one's posted an actual fix yet. I would've downloaded the latest client, BUT I re-installed CF yesterday after not playing for 6 months haha so how can it possibly be outdated? Is re-installing it the only way to beat it or is there something quicker I can do?
CF download speed from Wales is terrible.