I can't imagine that flying UK destined for the UK into an EU airport, and one three hours by road from the channel crossing is ideal. With perishables time is everything, and not just from a quality standpoint. Arriving late at wholesale markets knocks the value of the products right back, and making the supply chain so long, given the potential for "sh1t to happen", such as road closures, strikes, blockages, weather etc ought to make it a very risky business. Utilising a UK airport would appear very much more preferable on all levels, not least as at some time in the next 15 months the UK government is going to start full checks of agri-food products arriving from the EU which just shoves another potential obstacle into the supply chain.
Just a small percentage of the perishables arriving in the UK each week - no big deal.