Unfortunately, I cannot give you a definitive answer to your question. Nobody can honestly know what will happen to house prices post-Brexit, or to house prices in general, as there are far too many factors to consider at present. In the short-term, however, I can tell you that regeneration tends to give house prices an upward momentum, providing there are plenty of buyers looking to move into the area. Certainly, Whitfield does seem to be in the midst of a transformation of sorts, and the long-term indicators for the area seem positive. Do bear in mind that brand new houses often suffer a dip in value in the first few years after purchase, much as a new car does.
House prices in the south-east of England have raced up in recent years, and many observers feel that a house price correction is overdue. We saw such a correction in the 1990's after a similar period of property price inflation, and it should come as no surprise if Brexit were to trigger falls in values. That said, foreign investment in the UK property market remains strong. It's a tough call, and only you can know whether you're ready to commit to a house purchase at this stage.