At the time of writing (10:30 on the 6th July), we have 35 entries for the Nationals, you can see the entry list on SailScore here.
The discounted rate, of £146, for entries for the Nationals ends on Saturday 7th July. After this the rate is £166, so worth getting your entry in before the deadline. Entry online is available on SailScore. Pre-booking of tent pitches (you get two free per entry, but you need to book) and camper van spaces (no electric hook ups) here.