You do know that isnt how it works right? the EU doesnt have a budget that requires the amount of money that UK put into it to "make it work" since other countries will now benefit from the positives of being a member boosting their economy instead of britains. For instance Germany have been projected to have a labor shortage of 3 mio. ppl by 2030 which brexit will greatly help them overcome making their economy even stronger.
On the other hand britain will now face a higher cost of imports due to Tariffs which increases the inflation and reduces the standard of living for the UK citizens. Your export will also fall due to the elimination of the tariff-free trade status with the other EU members which is why several companies have already moved its HQ from britain to other EU countries. Also big international companies like Goldman Sachs and Morgan Stanley have already switched out a lot of their british clients with irish, french and german clients instead.