Hi Adi,
Thanks for your reply!
I'm not putting lit onto unlit so that'll be the first thing I try. My previous barbecue was much smaller than the current one so one chimney of charcoal worked pretty well. The chimney doesn't appear to be that big, it's a Weber and cost £20 so I guess they have bigger and more expensive ones.
I tend to leave the grill 20-30 minutes before cooking. I've only cooked on my new barbecue twice and neither time has the meat really sizzled when placing over the coal (I like to seal chicken thighs over direct then move over to zone 2). The coals came in a black and red bag. It did cross my mind that they might not be good enough but a bad workman and all that! I'll experiment with different coals too!
Thanks for the tips, just need the rain to stop now so I can try again!