I am going to buy it at Waitrose tomorrow now that I have reassurance. I will check with the person behind the counter that it's ok to keep until Saturday. I'm trying to leave all of Saturday free for cooking - and panicking
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The recipe is one a friend gave me after she made it some years ago. Very simple - you coat the fish with a clove of garlic crushed in mayo, the pile on a mixture of bread crumbs, parsley, lemon juice and rind. Put on baking tray with some cherry tomatoes on the vine, sprinkle all with olive oil and cook for 15 minutes at 220.
Thank you for all your help.