You may be lucky enough to get a tea or coffee on such a short journey but certainly don’t be surprised if you don’t get any food.
I was about to suggest Standard Premium but there are apparently no SP upgrades priced between Wilmslow and Manchester
I've never had food or drink on a first class ticket Wilmslow-Manchester. In the up direction the staff usually come round after Stockport, which is too late, and are invisible in the down direction (or they’re scurrying around ‘tidying’).
I used to use the Virgin-only (then Avanti-only) fares which started out at a discount but which now exist to trap the unwary and extort money. The Avanti-only day return, in particular, is now £18.70 versus the "any permitted" fare set by Northern which is valid on many more trains (admittedly mainly without first class accommodation) for 10p less at £18.60. It used to be priced at around £10.
Anyway, if you want the experience, buy the cheaper ticket and think about going via Manchester Airport in one direction also.
I no longer bother.