You can always learn in an automatic, then you don't have to think about gear changes. It does mean you can only ever drive an auto unless you retake your test in a manual, but it's always an option.
Remember you're not obliged to stay with one particular instructor so if you have a lesson and you don't like them, you can find someone else
Tell them that you're nervous, they're trained to deal with it.
Ask for lessons on a Sunday or during the day time (avoiding rush hour)when the roads are quieter you might find that once you get a bit more confident you can try different times of the day.
Look up different driving schools in your area, and ask your friends/family/colleagues who they used.
I was such a nervous learner, I didn't pass my test until my sixth attempt") which I get a bit of stick for but I've been driving for 7 years now and I love it
I lived in a little village with rubbish transport links so I had to pass my test if I had any hope of getting a job or getting anywhere basically.
This article might help
http://www.timesonline.co.uk/tol/life_and_style/health/features/article722210.ece
Some places offer off road driving lessons, these are usually for under 17s but they might let you do it if you ask.
If you do pass your test I would recommend doing Pass Plus as well - it's additional training covering and can help lower your insurance. There's the Institute of Advanced Motorists too which aim to make you a safer and more confident driver.
Good luck xx