£300 per month for gas/ electricity - £3600 pa This isn't huge if you have a larger than average house, and you need to prepare yourself for this to increase significantly, depending on when this payment relates to (if you are coming to the end of a fix set nearly a year ago, you need to factor in a price increase of more than double by April). Also you could use more if you're at home more. Probably worth investigating if it's worth investing in energy efficiency measures.
£174 Council tax per month - £2088 pa - average and not a lot you can do about without moving house. Which is something that you may wish to consider as a 6 bedroom house in London has to be worth a lot of money, that you could release a lot of by moving somewhere smaller in a cheaper area, which would allow you to keep up your lifestyle, travel, help DC out, whatever your priorities are. Although council tax won't necessarily reduce if you do this, because it's lower than average in a lot of places in London.
£90 Virgin Media per month - £1080 pa. Huge amount. Do you actually watch all the channels? You could get Netflix, Now TV Entertainment and/or movies for a tiny fraction of this amount. Or if you are determined to stay with Virgin, ring them and say you want to cancel because it's poor value for money and they will offer you a deal that is significantly cheaper, especially if you agree to take up their broadband (see below)
£47 BT broadband per month - £564 pa Quite high. We have fast fibre broadband from Virgin Media and it's fast enough for gaming, streaming etc. You can get this for £20-30 a month by starting on a deal and then swapping and changing or simply phoning at the end of each 18 month contract and asking for a deal to stay. I've done this twice, and they've immediately said yes both times.
£80 Water rates per month - £960 pa. Quite a lot, I'm guessing you're on rates. Moneysaving Expert's rule of thumb is that you'll pay less on a meter if you have fewer people than bedrooms. You're currently paying for the water use for a large family that no longer live in the property.
£470 House insurance per month - £5640pa. Previously discussed at length and only thing I can suggest is put some effort in here, talk to a broker, and read all questions you answer carefully so you're not admitting to problems that you don't need to because they don't exist and were a long time ago anyway.
£600 Cleaner per month - £7200 pa
£250 gardener per month - £4000 pa
Definitely worth cutting back if you no longer need their services, eg if you have more time to do the work yourselves. I'm sure they'll be able to replace the lost business easily enough, these types of services are often in high demand, they may even have waiting lists and you'll be able to provide them good references.
Annual fees
AA membership £272 Very expensive. Look at Autoaid, same service for £60 a year, otherwise, your car costs look OK.
Travel insurance 523.70 This is expensive but I don't know the impact of pre-existing conditions or if it covers worldwide travel and/or winter sports. Might not be able to reduce significantly.
I'm sure you might be able to identify other costs to cut. Have a look at the Moneysaving Expert money makeover to see if there's anything else you haven't thought of. It's not just for people in debt.
www.moneysavingexpert.com/family/money-help/