But Im thinking that surely that check-out would suffice as an LPC? If I was to take my logbook to the CFI (an examiner) and ask him to sign it off?
No, that won't be legal. Did you tell the Club that you needed a Revalidation LPC? If not, then it was hardly any fault of theirs.
basic difference between proficiency check and skills test is the nav
No, there is no difference in the requirements. Both the Revalidation LPC and the Renewal LST include a requirement for pilot navigation (although this can be replaced by an IMCR revalidation/renewal as part of the exercise). The extent of the navigation requirement is at the Examiner's discretion; he/she should take into account your pilot navigation recency when giving you the brief and setting you the task.