What language?

[#1]

I'm rebuilding my wesite using BlueGriffon & within the user manual it suggests using XHTML5 unless I have a strong knowledge of HTML or I require a specific dialect. As I have niether I will use XHTML5. Is this acceptable for Plusnet?

[#2]

It would be - I think it's down to the visitor's browser rather than the server.
However if you are intending to copy code from your existing site I suggest selecting HTML 4 Transitional. Your existing code complies with that but not HTML 5.
Or are you intending to start from scratch?

[#3]

Hi Spraxyt, I won't be starting from scratch. As we've discussed, I'll copy into notepad & then copy & paste into BlueGriffon. I'll probably be in touch many times. Best regards, Mick.