Something certainly doesn't add up, going by the figures you've stated.
To repay the 203k over the next 8 years would be £2115 a month before adding any interest at all, i.e. 0% interest. Your current rate is very low, so if you had the benefit of that for the next 8yrs £2200 a month would cover it. But current rates are about 5% at best, which would need £2570 a month to repay it. You've had the advantage of exceptionally low rates over the 14 years, but somehow not reduced the balance. Now rates are jumping up, you're going to take a spanking unfortunately.
Not sure what rates and deal you've had over the past 19 years. Or how much you've been paying per month (inc any over payments). But assuming an average 4% and no overpayments, you'd have been paying £1240 a month. But crucially, by now, year 19, your remaining balance should have been down to about 100k. You should have got down past 200k at least 10 years ago (by year 7).
I agree with the others that there's about 100k unaccounted for somewhere in all this. 5k credit card consolidation on a couple of occasions does not explain this at all.
As for what to do now - if you refix now, you'll be straight up to 5% immediately, and you'll probably have to pay an ERC (at best that'll be 2k, could be a lot more). So you'll be speculating on the current offers of 5% being better than what's available by next August, which yes, could well be even higher. But to change now would cost you around an extra £10k for certain (8k interest, 2k ERC).
I'm in a similar situation with my current fix ending later next year. Your choices are either to pay that 10k penalty up front to lock in 5% rate for an extra 4 years, or to take a chance on rates not going up much higher/coming down again towards the end of next year and keep your current fix for the remaining 10 months. If you've got savings, or ability to overpay regularly, I'd be inclined to chuck everything you can at it over the next 10 months and then take stock.
If mortgage rates are up to 7% next August then you'll be about 6k worse off overall, than taking 5.1% now. If they only go up to 6%, then you'll be 3k better to wait til then rather than jumping for 5.1% now. You should probably check all these calculations out for yourself though. Plenty of online mortgage calculators (I used the Money Saving Expert one for these estimates).
Check what your overpayment allowance is (typically 10% of the balance), and when it's annual anniversary is. If you're lucky you might be able to use two years worth of overpayment allowance between now and next Aug. Also bear in mind that at the end of your current fix, you should have the option to pay off lump sum of any amount without no penalty. Not sure exactly how that works if you've already pre arranged a new fixed rate to take over though?