Both the FTSE 100 and FTSE 250 UK share indexes are currently at record high levels. I am sure the weaker pound helps exports, but these levels are high. Of course, being shares, they could tumble tomorrow! At the moment, the stock markets are not phased by BREXIT.
UPDATE 1216z: FTSE 100 at 7110.43 (up 1.82%). FTSE 250 at 7110.43 (up 2.2%).