I'd agree with T-bird. You've now got 12 months MOT, so start using it.

If you did want to change, then be advised that a car like yours, the value drops as the MOT runs out. Especially when it gets to less than 3 months to go, and if selling it privately.

So IF you do want to change it, then ideally try selling it in 6-8 months time. I wouldn't bother trying to part-ex it in, you'll get offered a derisory price for it, unless you're buying something horribly overpriced. I'd sell a car like that on ebay, with a 99p start, and no reserve. You'd be surprised how many people will be after it. I've sold a few cars that way.

I do wish people (who never go under cars) would stop telling us that modern cars don't rust, the Ford Ka is a rust bucket, well known for it but not a bad little motor apart from that, get one new enough, rustproof it and you've got a decent little go kart.

As for this one, well you've got the welding done, had it serviced, couple of new tyres, if its driving OK just run the thing till the next MOT and when that comes up make the decision again.

With that in mind, do you think I shouldn't bother wasting my money on doing the rest of the welding (e.g. fuel cap/wing rust) but save the money towards new wheels instead?

Save your money towards essential repairs (hopefully not needed) or a newer motor when you finally decide to swap.

As you said in the tread title, "better the devil you know". Lods of money pits ihn your budget.

With that in mind, do you think I shouldn't bother wasting my money on doing the rest of the welding (e.g. fuel cap/wing rust) but save the money towards new wheels instead?

Hopefully the corrosion has been temporarily arrested. You have a not-very-old car with low mileage and recent new clutch (little old lady previous owner?! or has it been clocked - clutches should last over 100,000m if used properly) which should have a lot of life in it yet.

Don't spend money, apart from a wire brush, screw-driver, a can of Kurust and a can of good quality paint, e.g.Hammerite.

On a fine weekend borrow some little ramps and either you or a compliant friend crawl underneath and see where it has been welded and where there is any more rust. Scrape/chip/brush as much of it off as you can and then paint Kurust on it. Then apply the paint. Grease the brakepipes while you're at it - garages love failing these if only a hint of surface corrosion.

If a car appears to be looked after with such preventative maintenance (if done regularly a car should last indefinitely) it is more likely to pass the next MoT.

With that in mind, do you think I shouldn't bother wasting my money on doing the rest of the welding (e.g. fuel cap/wing rust) but save the money towards new wheels instead?

One thing occurs - you have fitted new tyres after the front ones wore on the inner edges. I don't know about tendencies of the Ka, but this sounds like incorrect tracking, maybe too much toe-out. If so, the new ones may wear the same way. It's cheap and easily corrected if that is the problem.