I have two kids (4 and 2 yo). Until now, they were both in nursery, but the eldest is starting school. Both my husband and I work in the same place and the kids were 50 mt. away from work. So we combined our working times and it was great (dropping them at 8 am and pick up at 4 pm, with me working from 6 am to 4 pm and my husband from 8 am to 6 pm)
Now I am lost about how to organise this new situation. I would like to keep the 2 yo in the nursery because he is very settled there and I like it very much too. But I need someone who would come home around 7.30 am to stay with my 4 yo and drop her at school. Many days I would need her to be picked up too, mainly until she starts afternoon sessions (her school decides when she is 'ready' for that).
I am foreigner and I have no idea of how to go for this one. I have always survived using the nursery and occassional help from family coming to give us a hand.
You should look at childminders - many of them do a school drop-off/pick up service to cover the house you need her looking after. Being in London there is bound to be one close to home/school that you could drop her at on your way to work. If she loves it and it works well, you could then always consider switching your DS there so that they get time together at the start and end of the day.
If you contact your local council's childcare department (you can get the phone number from here, they will send you an up to date list of childminders in your area. Most of them say what schools they do drop offs and pick ups for. There is also a list on that website I linked to but it tends to be pretty out of date.