You need to check with the employer, if they used your PPS number to tax you emergency as a once off employee then you should get a P45 which will show the pay and tax. Depending on the emergency tax operated you may have overpaid but you could balance that by filing the p45 and your regular p60 at year end.
If, although you provided PPS number etc. the employer has treated you as "self-employed" then you need to file that yourself. For small amounts you can do that at year end on the regular tax return Form 12 under other income.