Anyone filled out a W-8BEN form before starting a internship?

Yeah I did it:

1) Your full name
2) Put N/A as you are not an organisation. Could possibly put United Kingdom but I think N/A is best.
3) Tick individual
4) Full home address (use the one that is used by HMRC)
5) Ignore unless you want a different contact address
6) Leave blank/cross out (unless you for some reason have US tax number)
7) Put your national insurance number
8) I guess leave blank, if needed then your employer will add something here

9) Only tick box (A) and write United Kingdom in the blank (leave all other boxes unticked unless you have some special reason)
10 Leave blank

11) Leave blank

END - Sign and date and write "As Individual" for capacity in acting

Thats what I did - this all ASSUMES that you are a normal UK individual that has never lived or worked in the USA and has never conducted business in the USA from abroad. This is just a guide - check it all yourself, I take no responsibility