2) Will Brexit Affect Travelling from the EU?
There is no change until May 2019 and this date may likely be extended until December 2021.
But any change in the future will not affect your travelling to the UK to take part in Parallax Art Fair (no VISA will be needed and all EU citizens will be able to stay 6 months like US, Canadian, Australian and New Zealand exhibitors). It will also not affect your present tax situation when you sell work in the UK. You will pay the same tax that you pay now.