Yes I used the webform.
I told them about my holiday plans for the whole year- one in May (a total of six weeks - had to look after my mother in Germany) as well as the upcoming three weeks in September (again for my mother)
I attached a copy of my flight itinerary as well as a copy of my mother's passport, as proof of my mother's age and address as well as proof that I was really flying there.
I am aware that I did not have to do the attachments, but thought it showed that I "am a responsible citizen"
Beware though: it took them a couple of weeks to acknowledge the receipt of my submission and much worse it took them about 6 weeks to acknowledge that they had finally put the information into their computer system...
Nevertheless, it worked for me and I still got my test invitation for the end of July and my application seems to have been processed rather quickly.
Best of luck
Stef.