I need to replace my cycling shoes and I have big feet. This is an issue.
You know what they say: the bigger the feet, the bigger the… issues.
Throwing your budget of £140 to the wind, my suggestion would be to visit Cyclefit in London. A bit of a trek from York, to be sure, but it can't be helped.
This is an establishment which specialises in separating you from your money in the most pleasurable way possible. At least that's the impression I got from my visit yesterday. Bikes which the Agony household would only be able to afford with multigenerational loans hang from the walls. (I'm surprised they buzzed me in.) However, my interest lay elsewhere.
The very helpful Morgan Lloyd, resident physiotherapist, showed me a selection of the shims and inserts he uses to ensure each foot which comes his way is cradled for optimum performance. The bigger the foot, the greater the challenge, I'm guessing, so you would make his day.
The only flaw in my plan is he isn't actually a cobbler, as far as I'm aware. So you might want to keep this info on the back burner until you sort out procurement.
Get new shoes before it's too late