Thanks very much for the thorough advice. 
It is obviously not possible for me to do this then.
Maybe private hire taxi work would be possible for me then?
Budget £500 to get your badge.
You need the following:
DSA Taxi test, basically a strictly marked driving test, £78.
New medical, from your GP, to Hgv/Psv standard, £160 at my GP.
New CRB check, £44.
Licencing Conditions test, varies from Council to Council, but typically £25-30.
Badge, issued once all above done, again varies, but typically £200-250.
TFL website has all the info for the London Boroughs, or if you live a bit further out, your local authority will be responsible for the whole process.
If you want your own car, be vary carefull and ask lots of questions at your LA, as many have vehicle restrictions such as age/history/size and so on. First year Taxi insurance will be at least £1800, NCBs not transferable. Estate cars better as you can carry four people AND their luggage. MPVs cost more to buy, more to run, have crap luggage space, and are often only licenced for 5 passengers.
If you want to work for yourself, you will also need an Operators Licence for the place you live, again LA can help, these vary from £150-300.
As for not wanting to work 72 hr weeks, if you start out on your own expect to be on call 24/7, 72 hours per week is probably the minimum. If you work for a firm, using their car expect 30-40% commission, so £3-400 for every £1000 metered, taking your tax from that.
Using your car, commission will rise to 60-80%, possibly plus a fixed radio rental of around £100 per week, but you pay for fuel, car, tyres, servicing, repairs etc,etc...
And if you turn over more than £79k you'll need to be VAT registered.
Welcome to my world
