Hmmmmm......a little knowledge is a dangerous thing eh
Before you make post like this, maybe you should check your facts before making such assumptions as 'lack of competition', 'impartial' and by inference, price fixing on a public web site.
Croft, with the odd exception, has been £99 for the past two years from TTP, No Limits and Hottrax. The price charged by the circuit is the same for everyone and has increased for 2006 and as a consequence, in this instance, it has been passed onto the end customer.
The reason Croft don't have dates before May could be that they themselves decide to do this. Croft only have a set number of days a year they are allowed to run and I suspect see little point in asking track day operators to take such a huge financial risk as to book a date too early or late in the season to have any chance of filling it.
You have a point about impartiality, but not the right one I summise. The websites you conveniently provide a link to are not definitive/official websites in any way and there is no obligation to pay to have your trackdays advertised on a site or for the rider to also be charged for the privilage of booking through it. The best place to find No Limits and Hottrax dates is on their own websites or speak to them directly as dates can change at this time of year.
I think a comment about lack of competition in the UK trackday market is a little niave, when in 2005 3 established and respected operators ceased trading, namely, ESS, TTP and 100%. Let me tell you competition is fierce, profit margins are tiny or non-existent and the differentiation in the market is down to the quality of the day and sometimes a bit of luck with the weather, not a £6 price increase.