We stayed in a hotel next to Earls Court Tube station last time, which was handy as there is Filipino restaurant and two filipino supermarkets nearby. Also was fairly easy to get round and about. We stayed at the Shaftsbury Kensington which was fairly reasonable 3 star accomodation with modern rooms and cost 40 GBP for a night.
www.travelsupermarket.com is a good place for comparing deals on hotels, as well as laterooms.com, lastminute.com and booking.com
Whenever you find a good deal, it is always always always worth checking reviews on www.tripadvisor.co.uk as it will give you a good idea of what the hotel is like and whether you will be ok there.