Re-grading a Part-FCL PPL to a LAPL isn't an initial issue and shouldn't cost the figure you quote.
I did the online application and there is no option other than to apply for an initial issue of LAPL, although when I put my CAA number in it asked whether I wanted to add my night rating...so it must know my licence history. I haven't paid for it yet and have shot an e-mail off to CAA asking for clarification. I expect an answer, er, sometime. I'm not so bothered about pootling around with an instructor (who is also a pal so we can go off for the day and I can put him down as instructing) it's taking up non pilot passengers where I want to be squeaky clean as you can imagine.