Just went back to look at the details...

Initially I took 13k out mid-2021. Think the interest rate was around 4.5% on that one. Repayment was roughly £250 per month.

In June this year I topped the loan balance up to £15k and went for a longer term which kept the £250 monthly payment the same and gave me an extra £6k to throw at BTC. (So I've borrowed £19k in total)