I appreciate all the advice and am taking it all on board - which will of course lead to changes to my ideas since i am a novice.
Incidently, what are the capabilities of such boats as the MF/Antares 6m outboards? Are they just for fishing cruising a couple of miles out to sea? and fair weather only at that?
It is impossible to say, two miles out may be far worse than twenty miles out.
As I said before, one went round England.
They will be OK in a F2 or three, but an F 4 will become challenging, but dealable with a good skipper. (up to F4 it is calm weather). Then again, it will depend where the sea is coming from and where the wind is.
A F5/6/7 or 8 can build up very quickly.
Your boat will not sink easily, but there becomes the problem of collateral damage. Where systems break loose and things stop working.
Bigger boats tend to have two or three systems for most things, so can get by if things go wrong.
All boats need alot of respect and the smaller they are, need more.
Regarding your range. The prudent suggest, one third to get there, one third for problems and a third to get back home, if it goes pear shaped.
Boats that seems big enough in brochures and at the dealers feels so much smaller when out at sea. Comfort and features are limited in small boats also for living aboard.
The boats mentioned are designed for lighter use than you suggest, this meaning that they are meant to ideally perform on daytrips, weekends etc.
I'd suggest you feed your dreams by visiting marinas, talking to owners even of other types than you look for. Most like to tell, so listen and learn! Might even get invited to a trip out.
Talking budget: Just for comparison, check prices on used 'as new' boats to see if a larger boat is within reach.