See page 281, et seq, here:
https://www.sentencingcouncil.org.uk/wp-content/uploads/MCSG-April-2017-FINAL-2.pdf
You'll see that 'Abuse of position of power or trust or responsibility' (which is relevant when defrauding an employer) can take 'culpability' into the 'High (A)' category, as can 'Fraudulent activity conducted over sustained period of time' (i.e.when it's not just a 'one-off' fraud).
You'll also see that £5,000 is right on the boundary between 'Category 5' and 'Category 4' when it comes to assessing 'Harm'.
If the court sees your offence as 'A-4' (based upon the table on page 284), you'll further see that a custodial sentence is inevitable. The court, might, however, see the offence as 'A-5', 'B-4' or 'B-5', making a custodial sentence far less likely. (Note that an early guilty plea can see the custodial sentences there cut by a third, or non-custodial sentences reduced in their severity).
However (and here's the really important bit), nothing there suggests that a custodial sentence of greater than 2 years could be passed. That means that the court would have the option to pass a SUSPENDED custodial sentence. The likelihood of that happening is greatly increased by the fact that it's your first offence.
My guess (and it can be no more than that) is that you'll either be given a Community Order (typically involving a period of unpaid work) or, possibly more likely, a suspended prison sentence. Based upon reading countless court reports (and having done a bit of court reporting myself) I very much doubt that you'll be facing an immediate custodial sentence but it can't be totally ruled out.