Capital allowances when winding down

[Nessus]

I am slowly winding down my business as a self-employed computer consultant for the last 30 years or so. There is a residue of capital allowances in my accounts which has been going down at the usual 25% a year as I claim them against tax, and also going up a bit when I buy new stuff, though there is very little of that these days.

The allowances refer roughly 50-50 to the car and to other equipment such as computers. I have no plans to sell the equipment, and its resale value would be negligible anyway. I will probably trade in the car one day, but its value is already less that a sixth of what I paid for it, and will be even less at trade-in.

Is there any way that I can claim back these remaining allowances against the tax on my last few years of trading, or will I be stuck with a balance in the pool that I can never claim back?

Also, is there any potential tax liability from keeping the car, computers, etc., for personal use after stopping trading?

Would I be better off formally stopping trading, or should I simply keep the business open, declaring no income and no expenses in years when there is no work? I may well want to do the odd piece of work to supplement the savings, but probably nothing major.