Holiday pay question

dont know wether this is in the right forum but

was on holiday last week so friday went to the bank to get the previous weeks wages and theres nothing in , bugger thinks I as I’m up in scotland

so phones up my TM and asks why havent I been paid for last week, only to be told that you dont get paid till you come back off holiday the following friday

so after getting a bit peed off with him I asks to be put through to our MD who says that its right and I wont get that weeks wages till this friday and then my holiday pay the week after although that will only be a a day as I havent been there long enough to qualify apprantly

so after asking my father in law who is a union rep in the post office he reckons that my employer is in the wrong by not paying me last week and is actually witholding pay

is he right or is my employer right■■?