Hi Baz
Re: choice of boat, you do not say if you want it for family or purely for fishing. That aside the 535/536 are nice little boats but more suited to family uses as the cockpit space is a little limited. The Shetlands are well built boats and will give a fairly smooth/stable ride due to the gull wing hull configuration. You would be able to do all the inshore cruising and occasional fishing as well as towing skiers or blow up toys etc
The Wilson flyer however is a different beast, very suitable for the serious angler. They have plenty of cockpit space for anglers and gear. A harder ride than the Shetland due to the cathedral type hull, very stable at anchor and more than suitable for the area you intend to fish. You can still play with the toys as long as a suitable (50hp +) engine is fitted.
You do not need any legal documents or equipment to put to see in a small boat but I would suggest you look on our main page and take a look at our minimum requirements for our members http://www.pbsbac.co.uk/safetyequip.htm. Use this as a benchmark to putting you on the right road. The RNLI also offer free sea checks, if you are not a member of a club this might be a good idea. There is no pass or fail but they will give you plenty of advice.
I cant give you any advice re the area you intend to keep your craft as I dont know the area
Hope this helps
Martin