I have transported several boats down to Greece over the last few years, so hopefully can offer you some help. You will need:
Registration document - SSR is the easiest and cheapest way. See
http://www.mcga.gov.uk/c4mca/ukr-hom...smallships.htm. The SSR number must be permanently marked on the boat.
Proof of 3rd party insurance.
Proof of CE conformity if boat was built after 16th June 1998.
Proof of ownership - Purchase invoice.
Proof of VAT status
VHF Radio Licence for vessel and operator
Certificate of competence to operate vessel - ICC
The towing laws vary considerably from country to country. For example of France you will need to fit 80/90km stickers and carry 2 warning triangles (in addition to the normal driving kit). For boats over 2.55m wide you will need a special permit in most countries, but this should not apply to you.
Please feel free to PM me if you want any more advice.
Michael