I have sussed why I keep getting people coming to me with this search string: "What is the latest train to leave London for Manchester before 09:00?"
Another possible source is ngfl.northumberland.gov.uk/keystage3ictstrategy/Lesson 20plans/lessons 20pdf/8.3 20sample_teaching_u nit.pdf, for which I'm not going to put the link in, because I don't think I can access the National Grid For Learning.
So, for all you 11-14 year olds with the initiative to come to my site, here is the answer.
Simple answer: 8.00 Mondays to Fridays, 8.55 on Saturdays. On Sundays the first train does not leave until 9.05
More complicated answer: Timetables are available online at National Rail Enquiries. As you can see from above, it is important to check, because the times aren't the same every day.
Also, this is based on trains leaving from Euston. I haven't checked the times of trains from Paddington and Clapham Junction, because they take much longer.
You have to consider whether you really want to travel by Virgin trains, who are ironically regarded as being the most f*cked train service around (don't put that in your essay - you'll lose marks). I have found that especially when travelling to the suburbs of Manchester, it is actually quicker, at the weekends, to catch GNER to Wakefield or York, and Transpennine to Manchester Victoria.
You also have to consider whether 'timetabled to leave' is the same as 'leaving'. It has not been unknown for trains to sit at Euston waiting for a driver, or a signal, and then leave late.
But then, you don't really have any alternative to the train. I wouldn't recommend going by road - even if you were old enough to drive, which you aren't, driving is bad for the environment. Besides, you'll spend two hours just trying to pass Birmingham. You could fly, but flights at that time are more expensive. You will waste time travelling to the airport and checking in in advance. You will then have to travel from Manchester Airport to wherever, it's hardly worth it. Unless you're actually travelling from Slough or Crawley to Wythenshawe, in which case I would recommend the aeroplane. But I would advise against travelling before nine o'clock in the morning. It's cheaper later, and you get a lie in.
Do please come back and visit my site again. I would advise reading it from school, though, it contains some swearing.
Glad to be of assistance.