Hi im a primary school teacher, i told my head pretty much straight away for docs appointments n stuff....didnt feel the need not to tell her really. I didnt tell anyone else in school (apart from year group partner) until my 12wk scan...thats when i told children too.
If ur going on a residential i would probably inform ur head as u are better off having a risk assessment done for being pregnant on physical activities....its up to u tho hon, whatever u feel comfortable with. Suppose it depends on ur relationship with ur head/school???
Mine were fine with me telling them early plus i didnt feel like i was 'skiving' when i went for all my appointments hehee