It is a pity there seem to be no potential suppliers in the UK. There are some on the continent, but, err, perhaps they are holding their breath until it becomes clear what exactly will be the procedure of approval, and the cost thereof? The market will not be for hundreds of planes, meseemeth. Would it be worth the wager?
On a side-note, if I were a potential supplier from the continent, I would also hold my breath until it becomes clear the Brits have any money left to buy luxury goods such as recreational aeroplanes - as far as I understand, their economy is in for a serious decline due to Brexit, on top of the Corona misery. Also, I would wait a bit until it is clear what level of import duty will be levied; though I seem to understand the recent agreement steers clear of that horror, at least.
And by the way, all those 80-HP Rotax-powered two-seaters can easily operate with 500-600 kg take-off weight, they were only certified for 450 kg because that was the magical rule in those days. It is not a technical limit.