. It would probably be worth leasing some of the licences to (say) Spain for a while anyway while the UK fishing fleet gears up

So what you are saying is the UK fishing sector should invest in building up the fleet while it has no income, and will have no guarantee of success in winning a licence in future, and when the time comes to bid, have higher overheads to do with repaying for this new fleet whereas the Spanish (for example) have already covered a substantial part of those debts.