There is.... Once you are logged in and at the ISA dashboard, select "Transfer ISA" from the menu on the left, then there's a "Download Form" option in the "Transfer in" section.
I read in their FAQ though that you can only transfer in whole balances and only from CASH ISAs. Pity, I was hoping to split my lump sum maturing from a fixed term cash ISA in August so I could push 10k LW way. I might have to rethink that. :-(
I've just successfully done a partial transfer (in spite of my bank writing to me telling me they'd agreed to transfer twice what I'd asked for, which caused a bit of a panic until I confirmed they had done the right amount!!)
You'd be surprised how many erroneous cheques/transfer history forms we do receive from large, established ISA providers. Easily picked up though and normally resolved quite quickly.