Well done for passing your test

I would get a bigger van than an Astra, for the price your willing to spend I would get a connect or similar they can also hold more water, which you will need due to being new
I would definitely not use a back pack as a main system I would get a van mount without a doubt; back packs are good for odd jobs though.
Cards can work well as can leaflets, you need to remember that every man and his dog will be ticketing the same places as you, so just because you put out a 1000 a day (my guess is you will soon get bored of doing this) your card needs to stand out.
website is a good idea, start as you mean to go on, and make sure the address of it is on the card (I know this sounds obvious but so many forget this little detail)
It is quite refreshing seeing your determination and entrepreneurialism, just
remember to listen to good advice and you will save yourself time and money 
One thing go for a van mounted system over a backpack (did I already say that)