You would be better opening something like a Monzo or a Chase card. You get the bank rate at the time you do a transaction, no fees (except if a foreign cash machine charges but they have no control over it), and Chase's 1% cashback on everything is a lovely offer.
https://www.chase.co.uk/gb/en/?utm_source=google&utm_medium=paid_search&utm_campaign=mkt-469_uk_gl_bau_sea_gg_acq_xdv_pr_adp_at1_brand_features&utm_content=brand_chase_cards_exact&utm_term=chase_card&ds_rl=1299624&ds_rl=1299624&gclid=CjwKCAjw9J2iBhBPEiwAErwpebCLskVOuVFJY6WbNbx7EAFqhJKl81nFZvyjKiRqcxpnqAq4OTuYtRoC9oMQAvD_BwE&gclsrc=aw.ds
I believe the travel cards mentioned above lock in the currency rate at the time you buy it so you can lose out by doing this. Obviously you can also gain, but that's the risk you take.