Will I get a tax rebate?

[ClaireandGeorge]

I was on smp from January - September, then when back to work part time, was bringing home just over £600 which I wasn't taxed on. Since December - Mid March I have been full time covering someone else's mat leave. I have paid tax in these months bringing home just over £1000 after tax. Should I get a bit/all of it back come April?

not necessarily, if your tax coding is a cumulative tax coding (ie 810L) any tax due back to you would have been paid via your pay, they rarely pay you back tax at the end of the tax year these days.

I'll have a look at my tax code on my pay slip then. The other girl who I job share with (she covered my mat leave and I covered hers) said she recently got some tax back, perhaps that was in her mat pay wages.

Asuming this is all with thr same employer, then probably not

You can check here if you can estimate how much you will earn for the whole tax year
www.mranchovy.com/calc/