Il follow this thread with interest.. your circumstances are nearly identical to mine.. Mainly fished from shore but recently invested in my first SIB itís a 2nd hand Plastimo 2.4 with a 2HP outboard... Iíve only got that set up as it was relatively cheap and literally allows me to test the water and whether my interest will develop... long term aiming for a Honwave 3m ish and a 9.9 outboard..
In terms of fishing at sea and in estuary I think a lot will depend on your set up in terms of limitations..
At the moment im exploring waters around Maldon and also due to venture to Mersea Island soon... tho limited due to my beginner status in terms of knowledge of tidal strengths winds/weather and the obvious limitations of a small outboard.
Whatís your set up and where would you ideally like to fish?