However, carrying companies (airlines, ferry companies and eurostar) can refuse boarding to someone who have no form of ID because they could be liable under the Carriers Liability Act of fines up to £2000 for carrying an undocumented passenger (sorry slightly off topic but felt clarification was needed).
The problem I will have next month going to France with Ryanair, is that my UK Passport is still in my male name, therefore I will have to dress as to passport foto. I will see what I can do as to getting a letter from GP etc, but I do not think there will be enough time on this trip and I don't think it will be enough to get my passport changed over to female from male, without transgender reasignment certificate.