Welcome to the forum Rodders. I'm a bit further north. Usually boat as far south as Montrose. Nice part of the world - but North Sea usually has a chop on it. Some good fishing, mackerel, cod, haddock, dab, etc.
Arbroath has their own webcam - so you can see first hand conditions, as well as advance weather planning via Met Office and XC Weather.
https://visitangus.com/webcams/
Only thing I can add - I used to run a Zodiac GT MKII CGT when I was a teenager with aluminium floor and 25hp (Yamaha 25D). That was for holidays on the west coast, so we would build the boat and it was up for 2 weeks.
Building from scratch on a slip will reduce your time on the water, plus you need to consider how it's transported. Lugging a 4-stroke out of the back of a car isn't fun, unless there's two of you.