Posting Payslips & Tax Credit Cert?

So we submitted my wifes eu1 form 3 weeks ago just got a copy my first payslip is it best to forward this stuff on as you get them? still waiting for tax credit cert? i wrote a covering letter that i would forward the payslips as i get them, is it ok to post photocopies or should i post the original payslip?

For payslips, you can submit photcopies. Actually for all documentation except passports and marriage/birth certificates, you can submit copies