Laurence,
I’m sorry to seem harsh but you need to have a Reality Shake with this 'ol shaker.
( I run a 28 years old Eunos Roadster and my wife’s is 3 years older than yours, so we know our way around them to say the least.)
By Reality Shake, your car is bordering unroadworthy & potentially dangerous…and is basically what my two were like before I had them restored & refurbished…it’s marching into shed/ spares- project repair status. In fact, in my view…it’s there now.
Leaky exhaust, perishing cracked tyres, and multiple “minors” which in isolation are not a great big deal on their own, but put into the same basket…are.
Corrosion? As has been pointed out to you quite clearly…it’s approaching rust bucket status…and in another year or less could be better scrapped.
Who knows? You need to get it ramped pronto and have an MOT chap or chapette who does not mince his or her words…and drill to the bottom line.
In it’s current condition on several levels I’d not take your car from Scotland down the M6 to Brum at any speed…put it that way. For money or a bet. . I’d be waiting for blow out for starters, not to mention a rotting tub no way has the same crash integrity as a solid one.
As it stands…it all appears to be fixable with a suitable amount of wad chucked at it.
Only you can decide whether to ditch it and pay off the finance, or restore…but for sure…one way or another you won’t be driving it as is…while paying for it.