Spend some of that money on coaching, bump up the batting order by 3 places, then earn back the money spent on coaching and invest £300 on a bat.

You are really spoilt for choice on this forum. £150 is more than enough to get a really top quality bat if you look carefully. The boys at B3 really are churning out some quality bats, I've had 2 pass through my hands, one which I've still got and the other my friend bought off me. They are both 1 stripes, (Grade 3) but play superbly. If you are looking for a Grade 1 bat, I think Vitas Cricket can source you a lovely Hunts County Grade 1 Custom for £165!
In all seriousness, some one on one coaching does help tons. I have a friend who didn't just work on grooving out shots with me, but helped me think about how to manoeuvre the field placings and remove the slips, so I could milk 1's and 2's via my strongest shots. I'm afraid we can't all score boundaries at will like Dhoni, Gayle and AB!
Set yourself a budget, and decide for yourself what kind of a profile and grade you want, and what kind of branding you like. Sounds crazy, but I believe the look of the bat to the user can make a psychological difference for most people.