I’d say if the 3% was a lot higher then there’s more incentive to reduce quicker.
As mentioned above it’s best not to think about gaining interest when you’re paying interest, I guess about £2,000 for borrowing £13k over 5 if you made no additional payments. So it’s better to work on reducing that I guess ~£33 a month in interest rather than trying to gain a few quid elsewhere.
You’ll need to obviously check the loan agreement on any penalties for early repayment.
But you might as well put in Marcus to build a small emergency first like one or two months expenses covered and earn the most whilst still having instantish access.
I’d stay with your parents for as long as possible as it’ll be much easier to save/payoff good chunks.