I got this a bit wrong. The eclipse starts at 01.10 but only with the earth's penumbra. The total eclipse doesn't start until 03.11 but it continues until 04.22 so there is plenty of time to wake up, go for a pee, watch the eclipse and still get a few more zzzz's in before breakfast.
There is a brilliant animation here:
http://www.timeanddate.com/eclipse/in/uk/portsmouth