Ah
@Fubar - what have you got yourself into now ??

'My first Audax' so you're doing one of the Musselburgh dentist's finest ? He doesn't organise anything without at least a gazzillion AAA points … or so I'm told, never having been fit enough to do any of his rides !
That said (and a great disservice to him it is

) you'll be fine. The largest part of a 200 is in yer heid. Your legs - as long as you continue riding as you are - will be fine. If anything is to go it will be your head telling you silly things like "I'm going too slowly; I'm not going to make it; that hill is one too many" etc. Tell your head that you can and are going to finish and within the time limit and that's that !
Lots of much more capable amd experienced audaxers have given you excellent advice but if there is anything you want to discuss with me, get in touch and we can have a wee ride around and a chat. I might even have a Carradice Barley with the support rack for sale … then you will
really look like an audaxer …