Two associations control the Trent at Winthorpe, Worksop have two and Ashfield AA have one thats in the middle of the two Worksop waters.
Both require membership and Worksop AA dont allow night fishing.
The Worksop book is pretty reasonably priced, the Ashfield club is pretty expensive and has a long long waiting list of prospective members.
If you only plan to fish Winthorpe on the odd occasion it may be better for you to approach the river from the A1 pits side of the river where I understand
You can drive all the way down to Winthorpe (a very long reach of river)
on a day ticket.
Ps, it only rises and falls when flooding.
The tidal section is somemile and a half downstream at Cromwell weir!
Hope this helps.