I think 27 foot would make the trip somewhat of a different adventure than on 32 foot, which in itself would be a tad different from 40 foot (albeit not such a big leap as from 27 to 30 plus).
In addition to the boat simply being smaller for self / crew and storage
(more space is
better! Not an absolute requirement, but nonetheless better) - also a smaller boat will be harder work on passage
simply because the smaller the boat the more input she will require from the helm
/ crew as more at the mercy of (in tune with?!) the sea and wind
- even in good weather. As a broad comparison like having a motorbike vs having a car - motorbike lots of fun! and even long trips are enjoyable but often enough a car does make life more pleasant, not only in bad weather 200 miles from home but simply when doing dull stuff like eating lunch........
Am not saying not possible (nor not "safe" - loads of 27 footers gone far and wide) - but IMO the smaller the boat the more seaworthy
in design it needs to be (and in good condition), larger can more often get away with simply being larger).......but upsides as well, especially on the less money spent.........Everything about boats is about compromises and trade offs and sometimes those made with less than perfect information.
IMO £20-£30k as a buying budget
is decent enough (even at UK prices) for some decent options without needing to go down to 27 foot - albeit also enough to buy a chunk of someone else's problems!, especially as will be fishing
in the boat pool marked "Older".....a wade through the Project
boat thread (in my sig below) might help reinforce that you do not want to buy a project boat (aka in Broker / Vendor speak as "some TLC required"!), especially not unintentionally!
Also, if not done so already, have a look at the Cruising Equipment list in my sig below - the collected wisdom of CF! Work out what you want onboard and that may help dictate the size of boat as well as help decide what you need to buy with the boat (do some totting up of the ballpark numbers!)......also remember that Solar Panels
are big - and often a struggle to fit on decks of any size, at least in places that are out of the way!