it's a nice and decent phone. good choice and that speaker is the icing on the cake. as soon as you get your phone just go through the claims process, the quicker the better... if you leave it too long then it expires.
oh I've not bought the A51 and don't own the speaker. I just know the offers well, I try to keep up to date with what's going on. I've recently purchased the Samsung Tab S6 Lite on a contract through EE and I've done my claim for the buds. the claim has been verified by their verification team (you have to upload proof of purchase to them, cause yours is delivery I'm guessing it will be the delivery note that will come with the order) just got to wait for the next notification. from this forum I'm pretty certain that Yodel will deliver my buds... your speaker is higher retail value than the buds.