I would forget getting an AOC for charter. It's a mug's game. You spend 5 digits getting the AOC and all you can do is the occassional ferry of a bunch of golfers somewhere, and will need a twin for that, which is another black hole for money - especially if you get some old heap like most of those I see doing AOC work.
Try telling London Executive that! Many small AOC operators start out of clubs. It is a specialised market, and it is a bad time to start now, but certainly worth considering getting a twin to do some training on and to hire out with a view to AOC work later on, simply because prices are low at the moment. An A-to-A certificate (i.e. only pleasure flights, no flights to other airfields) is rather easier and cheaper to achieve than an A-to-B, and even worth looking at for a single, as you only want to fly day VMC anyway.
Just look at the current market, see what other people have made money flying. Don't assume you have found a brand new way of doing things that'll take all the business from your competitors. That is how larger amounts are lost! Don't even consider doing back-door charters/pleasure flights without an AOC (or hiring them the aeroplane, putting them in touch with a pilot you hapopen to know). The other operators are watching, and I know of four companies/individuals who have had to answer to the CAA, and only one who got away with it. Not good odds!