Hi Ziplex,
Not difficult to guess you're a beach man with that name.
Anways, welcome aboard.
If you are intending to stay within Poole Harbour, try these spots:
Drift the main entrance to the harbour between the Chain Ferry and Brownsea Island. Keep well clear of the Ferry Crossing and be careful during peak times 'cus the entrance can be like the M3!! Best fishing early morning or evening for the bigger specimens of bass. Spinning and sandeels. Note that you cannot anchor in the main channel.
In front of Brownsea Castle around the pier area, drift for small pollack, pout and wrasse on worm baits, bouncing just off bottom.
The Wych channel which runs around the east and north side of Brownsea Island. Find a place to anchor up and fish into the channel. Rag will take school bass and flatties.
The area in front of Blue Lagoon in the shallows. Worms baits will take schoolies and flatties.
There are loads of other places, but try these to begin with, and keep a look out for where other boats are fishing.
Baiter is your best choice for launching, but avoid extreme low tides. Note that Poole Harbour has a double tide each day.
cheers
Bob F.