So I spoke with Bk this afternoon, the P12 are waiting on speaker parts around 5 weeks and the price is more than likely going to go up due to new shipping cost. They suggested the Double gem with a 2 week lead time (above) but I'd prefer a DF for aesthetics.
Are there any other DF subs in white recommended in a similar price bracket.??
No DF and nothing in the 400£ range that would be comparable performance wise to P12. Next white compact sub would be SVS SB1000 about 560£ if you get AVF member discount. Clearly over your budget.