Depends on personal circumstances. A newer car is always nice right?
But, it doesn't appear to be so many changes with Panda? (Someone will crucify me for saying it!).
If the bank allows, replace, if not, fix. But 150 miles a month - Hmm... Fix.
I would do cambelt now and wait for this current price hike to pass and look at your changing options again in 2023. By then the panda hybrids will become reasonable prices and will be 2 or 3 years old and start being more available after 3 tear lease releases. Today I did a 35mile commute from high wycombe into North Oxfordshire and returned home on less than a gallon of petrol all in a 1.0 firefly hybrid sport at 70.9 mpg, its not even loosened up yet at 5.600miles. Once you've been driving the mild hybrid for a while you get good numbers out of them. They also don't have any dead bands like the euro 6 cars.
My Panda is now 16 years old, passd a recent MOT with no advisories. Only done 85k miles, but is mostly used twice a week for a 25 mile round trip. I do a monthly 80 mile round trip, and now will be looking at a 190 mile round trip monthly. I will do most of these in the Panda, in preference to the 2015 Fabia. The Panda is a happy car, it makes me smile. Newer cars, not so much.