Stick with the diesel or switch to EV?

Hi all, I really need some advice as I’m a bit torn on what to do.

I’m currently driving a 2017 diesel on about 155k miles. It’s starting to show signs of wear (rattling/juddering) and I suspect it could need a few thousand spending on it soon. It’s probably worth around £5–7k as it stands.

I do roughly 3k miles a month, so running costs are high. At ~38 mpg and diesel around £1.75–£2/litre, I’m spending £600–£800 a month on fuel alone, plus the risk of repairs.

I get paid a flat rate of 45pence per mile for work.

I’ve been looking at switching to an EV at around £15–20k. I can charge at home cheaply, so my monthly “fuel” cost would drop to maybe £50–£70. On paper that’s a big saving and removes the risk of big diesel bills.

The complication is I’ve recently paid my debt down from £24k to £10k and I’m overpaying about £900/month to clear it. I’ve also got a mortgage renewal coming up in ~12 months, so I was hoping to reduce my debt further before then.

I’m basically stuck between keeping the diesel another 6 months to hammer the debt down (but risk repairs and high fuel costs), or switching now to cut running costs but potentially taking on finance again.

The bit I’m struggling with is I don’t want to undo the progress I’ve made on the debt and despite finding some really good EV deals, I cant pull the trigger, even if switching would save money longer term.

What would you prioritise in this situation — clearing debt and keeping things clean for the mortgage, or reducing monthly running costs now?

Appreciate any thoughts.