Hi Guys - I'm awake in the middle of the night with period pains so thought I may as well pop on whilst my cup of tea cools enough for me to take tablets!!
Thanks for your comments on my half.

Hope your half on Sunday goes well Flo Po.
Mitiog - my 92 year old grandma had a similar attitude to your mum. When she sponsored me she told me that she couldn't believe how far I was going to run but not to worry because she would pay whether I finished it or not and "don't slog your guts out because it is not worth it. If you feel too tired it is better just to stop"!!
A 32 minute PB may be possible Mitiog - I did a 30 minute one

My advice would be don't put too much pressure on yourself to do sub 5. I would love to have a PB which starts with a 4 but a PB is a PB.
I followed advice (which I may have got on here actually) to have 3 times in mind - a perfect scenario, a good time and something you would settle for which worked for me as I'd done 5.49 previously so my 3 times were 5, 5.15 and 5.30 and in the end I was delighted with my 5.19. That way when time slips away you won't panic and you won't feel disappointed when you done a PB if it isn't your ultimate goal PB!
I did the first 11 miles of London at 11.20 pace which felt comfortable but with short stops for gels and to say hello to supporters and then the last section when I ran-walked for a bit I still ended up with a average of more than 12 mins (and remember that you will run further than 26.2 - I did 26.7).
If I don't get chance to post again before Sunday (I'm going on holiday on Saturday and haven't thought about packing yet) have a great run Mitiog. Enjoy every minute of it and good luck for a PB you are really happy with