What an excellent collection of advice. I must admit I would encourage you to go as soon as possible, take up one of the kind offers to share the trip and enjoy a great lunch in France. One thing that I did not notice is mention of Fuel Excise Drawback. This is one form that I never mind filling in. Every time you fly out of the UK HM Customs and Excise will pay you 27.34 pence for every litre of fuel you can squeeze into your plane. This is because you are exporting the fuel and they give you the duty back. I go to the South of France in my plane every month and each month they send me a cheque for £130. It will be less for smaller planes but it will certainly pay for your lunch and your landing fees.
The best thing I ever did when I first got my PPL was find two friends who were outstanding pilots and fly as much as possible with them. I suspect some of those above offering to go with you may turn out to be yours!
Finally, remember that to an instructor whose live quite literally revolves around the circuit a trip in the right hand seat with you will seem very appealing.